WO2017217546A1

WO2017217546A1 - Method for manufacturing multilayer sheet, method for manufacturing molded container, and multilayer sheet

Info

Publication number: WO2017217546A1
Application number: PCT/JP2017/022396
Authority: WO
Inventors: 茂樹工藤; 実川▲崎▼; 茂実杉山
Original assignee: 凸版印刷株式会社
Priority date: 2016-06-17
Filing date: 2017-06-16
Publication date: 2017-12-21
Also published as: JPWO2017217546A1; JP6954281B2

Abstract

Disclosed is a method for manufacturing a multilayer sheet that has a thermoplastic barrier film formed by stacking a base material that contains a thermoplastic resin, a first barrier layer that contains a polycarboxylic acid-based polymer and a plasticizer, and a second barrier layer that contains a polyvalent metal compound and a resin. This manufacturing method comprises: a step for preparing the thermoplastic barrier film; a step for preparing a polyolefin resin composition and an adhesive resin composition; and a step for extruding the polyolefin resin composition and the adhesive resin composition from an extruder so as to feed the thermoplastic barrier film and position the adhesive resin composition between the fed thermoplastic barrier film and a layer formed by the polyolefin resin composition.

Description

Multilayer sheet manufacturing method, molded container manufacturing method, and multilayer sheet

The present invention relates to a method for producing a multilayer sheet, a method for producing a molded container, and a multilayer sheet, and particularly relates to a method for producing a multilayer sheet used for boil and retort applications, a method for producing a molded container, and a multilayer sheet.

Compressed heat sterilization may be performed on packaging containers as a retort treatment for long-term preservation of foods. When ethylene vinyl alcohol copolymer (EVOH resin) is used as a gas barrier layer for a packaging container sheet for such an application, since it has low resistance to humidity, hot water, etc., a significant decrease in barrier performance called retort shock Occurs. Therefore, Patent Document 1 proposes a thermoplastic barrier film in which a layer made of a mixture of a polycarboxylic acid polymer and a plasticizer and a layer made of a mixture of a divalent metal compound and a resin are laminated. According to the packaging container provided with the thermoplastic barrier film described in Patent Document 1, since the thermoplastic barrier film exhibits a barrier property by the hot water treatment, a retort shock seen in EVOH resin or the like does not occur.

Japanese Patent No. 4397895

However, in Patent Document 1, a thermoplastic barrier film and a sheet made of a thermoplastic resin are produced separately, and after both are produced, the thermoplastic barrier film and the sheet are dry laminated through an adhesive to produce a multilayer sheet. is doing. For this reason, the multi-layer sheet described in Patent Document 1 has a problem that it takes time to manufacture and the productivity is low. In addition, when dry lamination is performed, there are restrictions on manufacturing conditions, and for example, it is difficult to process a sheet having a thickness of 1 mm or more (a limited processing machine is available), and thus a multilayer sheet having a predetermined thickness or more is manufactured. There is also a problem that it is difficult. Moreover, there exists a squeeze container as one of the packaging containers using such a multilayer sheet. This is a container form that squeezes the required amount by crushing the container, and is suitable as a seasoning such as mayonnaise or mustard, or a liquid food container such as pet food or baby food. Here, since the thickness and the oxygen barrier property of the EVOH resin are proportional, the improvement of the oxygen barrier property and the improvement of the squeeze property (= thinning) are contradictory. Therefore, it is difficult to secure squeeze properties with a high barrier container that is intended for longer-term storage.

Accordingly, the present invention provides a method for producing a multilayer sheet, a method for producing a molded container, and a multilayer sheet, which can increase productivity more than before and can flexibly cope with many different product specifications. Objective. In addition, as another aspect of the present invention, as a use of the multilayer sheet, the squeeze can be easily squeezed out, and the high barrier property that does not depend on the thickness of the container and does not cause deterioration of the barrier property due to the heat sterilization treatment. It aims at providing the squeeze container which has the property.

The present invention, as one aspect thereof, relates to a method for producing a multilayer sheet. In this multilayer sheet manufacturing method, a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid polymer and a plasticizer, and a second barrier layer containing a polyvalent metal compound and a resin are laminated. A method for producing a multilayer sheet having a thermoplastic barrier film, the step of preparing a thermoplastic barrier film, the step of preparing a polyolefin resin composition and an adhesive resin composition, and supplying a thermoplastic barrier film And extruding the polyolefin resin composition and the adhesive resin composition from an extruder so that the adhesive resin composition is located between the layer formed of the polyolefin resin composition and the supplied thermoplastic barrier film. And.

In this method for producing a multilayer sheet, the thermoplastic barrier film is adhered to a layer formed of the polyolefin resin composition serving as a sheet base material with the adhesive resin composition, and therefore, in the step of extruding, the thermoplastic barrier film is used. While supplying the film, the polyolefin resin composition and the adhesive resin composition are extruded from an extruder so that the adhesive resin composition is positioned between the layer formed by the polyolefin resin composition and the thermoplastic barrier film. I am doing so. In this case, when extruding the polyolefin resin composition to form a polyolefin layer, the polyolefin resin composition and the thermoplastic barrier film are also bonded together by thermal lamination. Since the dry lamination step using an adhesive that has been performed again after the production of this sheet can be eliminated, the manufacturing time can be shortened and the productivity of the multilayer sheet can be increased. For example, assuming that the line speed when a thermoplastic barrier film and a 0.6 mm thick polypropylene sheet are bonded by dry lamination is 30 m / min, when producing 100,000 m per month, at least about 60 by only dry lamination processing. It takes time. However, by adopting the manufacturing method according to the present invention, such a dry lamination process can be omitted, so that the time can be significantly reduced and the productivity of the multilayer sheet can be greatly increased. In addition, as described above, in this method for producing a multilayer sheet, a thermal laminate is used, so that it is possible to easily produce a polyolefin layer having a thickness of 1 mm or more, compared with a production method using a dry laminate. Therefore, it can flexibly respond to many different product specifications.

In the above multilayer sheet manufacturing method, the adhesive resin composition preferably contains an acid-modified polyolefin. In this case, since the functional group imparted to the polyolefin is bonded by a hydrogen bond with the metal oxide contained in the surface layer of the thermoplastic barrier film, the thermoplastic barrier film and the layer made of the polyolefin resin composition serving as the sheet base material It becomes possible to increase the adhesive strength. The adhesive resin composition used here preferably includes a graft-modified polyolefin obtained by graft-modifying or copolymerizing at least one polymerizable ethylenically unsaturated carboxylic acid or derivative thereof with a polyolefin resin before modification. .

In the above method for producing a multilayer sheet, the adhesive resin composition may have a melt flow rate (MFR) of 3 g / 10 min or more. In this case, due to the flexibility of the adhesive resin composition, high adhesive strength between the adhesive resin composition and the thermoplastic barrier film can be maintained even after the sheet is deformed by molding.

In the above multilayer sheet production method, the adhesive resin composition preferably contains an acid-modified polypropylene resin or acid-modified polyethylene resin and a resin modifier made of an α-olefin copolymer. In this case, flexibility can be imparted while maintaining a melting point that can withstand retort treatment and the like.

In the above multilayer sheet manufacturing method, in the step of extruding, the adhesive resin composition may be extruded so that the thickness of the adhesive resin composition is 1 μm or more and 50 μm or less. When the thickness of the adhesive resin composition is 1 μm or more, peeling between the thermoplastic barrier film and the layer formed by the polyolefin resin composition can be suppressed, while the thickness of the adhesive resin composition is 50 μm or less. Thereby, the usage-amount of an expensive adhesive resin composition can be reduced, maintaining the adhesive force required.

In the method for producing a multilayer sheet, the extruder is a multilayer extruder, and in the extruding step, the adhesive resin composition overlaps the surface on the thermoplastic barrier film side of the layer formed by the polyolefin resin composition. It is preferable to co-extrude the polyolefin resin composition and the adhesive resin composition from a multilayer extruder. In this production method, the adhesive resin composition is first extruded using a single layer extruder, and then the polyolefin resin composition is extruded to form the adhesive resin composition with the polyolefin resin composition. The polyolefin resin composition and the adhesive resin composition may be extruded from an extruder so as to be positioned between the layer and the thermoplastic barrier film. By coextrusion of the composition, the production rate can be increased and the production efficiency can be further increased.

In the method for producing a multilayer sheet, in the extruding step, the polyolefin resin composition may be extruded so that the layer made of the polyolefin resin composition has a thickness of 1 mm or more. As a product specification of the multilayer sheet, there are cases where the layer portion formed by the polyolefin resin composition requires a thickness of 1 mm or more, but in dry lamination, it is difficult to process a sheet of 1 mm or more. However, according to the method of the present invention, even a layer formed of a polyolefin resin composition having a thickness of 1 mm or more can be easily produced, so that a compatible product group can be widened.

The present invention relates to a method for manufacturing a molded container as another aspect. This method for producing a molded container includes a step of producing a multilayer sheet by any one of the above-described methods for producing a multilayer sheet, and a step of producing a molded container by stretching the multilayer sheet. In this case as well, it is possible to achieve the same effects as the above-described multilayer sheet manufacturing method.

The present invention also relates to a multilayer sheet as another aspect. This multilayer sheet is a multilayer sheet including a polyolefin resin layer and a thermoplastic barrier film attached to one surface of the polyolefin resin layer with an adhesive resin layer. In this multilayer sheet, the thermoplastic barrier film includes a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid polymer and a plasticizer, and a second barrier layer containing a polyvalent metal compound and a resin. The thermoplastic barrier film is attached to one surface of the polyolefin resin layer with an adhesive resin layer, and the adhesive resin layer contains acid-modified polyolefin. In this case, since the thermoplastic barrier film is a film in which a first barrier layer containing a polycarboxylic acid polymer and a plasticizer and a second barrier layer containing a polyvalent metal compound and a resin are laminated, heat and moisture resistance characteristics It can be set as the multilayer sheet excellent in. Moreover, since the polyolefin resin layer and the thermoplastic barrier film are bonded together by the adhesive resin layer without using an adhesive, it is possible to produce a multilayer sheet without using an organic solvent generally contained in the adhesive, It can suppress that the odor of the remaining organic solvent transfers to the content arrange | positioned in a multilayer sheet (or shaping | molding container shape | molded after that), for example, foodstuffs, and reduces the flavor of a content.

According to the present invention, it is possible to increase the productivity of multilayer sheets and flexibly cope with many different product specifications.

It is sectional drawing which shows the multilayer sheet which concerns on one Embodiment of this invention. It is a figure which shows typically the process for manufacturing the multilayer sheet | seat shown in FIG. 1, (a) shows the manufacturing process of a thermoplastic barrier film, (b) shows the process of carrying out heat lamination of the thermoplastic barrier film. Show. It is a figure which shows the process for manufacturing the conventional multilayer sheet typically, (a) shows the manufacturing process of a thermoplastic barrier film, (b) shows the manufacturing process of PP sheet. It is sectional drawing which shows an example of the shaping | molding container manufactured using the multilayer sheet shown in FIG. It is sectional drawing which shows the squeeze container which concerns on one Embodiment of this invention. It is sectional drawing which shows the other example of the multilayer sheet which concerns on one Embodiment of this invention. It is a figure which shows one form of the container for evaluating the Example and comparative example of this invention.

Hereinafter, a method for producing a multilayer sheet according to an embodiment of the present invention will be described in detail with reference to the drawings. In the description, the same reference numerals may be used for the same elements or elements having the same function, and redundant description is omitted.

FIG. 1 is a cross-sectional view showing a multilayer sheet according to an embodiment of the present invention. As shown in FIG. 1, the multilayer sheet 10 includes a substrate 1, a barrier layer 2 provided on one surface of the substrate 1, and a polyolefin layer 3 provided on one surface of the barrier layer 2. The barrier layer 2 and the polyolefin layer 3 are adhered to each other by an adhesive resin layer 4 made of an adhesive resin composition. The barrier layer 2 includes a first barrier layer 5 containing a polycarboxylic acid polymer and a plasticizer, and a second barrier layer 6 containing a polyvalent metal compound and a resin. A thermoplastic barrier film 7 is constituted by the base material 1 and the barrier layer 2 composed of the first barrier layer 5 and the second barrier layer 6. When the multilayer sheet 10 is formed into a packaging container or the like, the polyolefin layer 3 side (the upper side in the figure) of the multilayer sheet 10 is the side in contact with the package contents, and the base material 1 side (the lower side) of the multilayer sheet 10 is the outer side of the container. It becomes.

[Substrate 1]
The base material 1 is a base material of the thermoplastic barrier film 7 and includes a thermoplastic resin. The type of the thermoplastic resin constituting the substrate 1 is not particularly limited. For example, polyolefin polymers such as low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, poly-4-methylpentene, and cyclic polyolefin are used. And their copolymers, and acid-modified products thereof; polyvinyl acetate, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, and other vinyl acetate copolymers; polyethylene terephthalate, Aromatic polyester polymers such as polybutylene terephthalate and polyethylene naphthalate and copolymers thereof; aliphatic polyester polymers such as polyε-caprolactone, polyhydroxybutyrate, and polyhydroxyvalerate; and copolymers thereof; Nylon 6, nylon 66, Polyamide polymers such as Iron 12, nylon 6,66 copolymer, nylon 6,12 copolymer, metaxylene adipamide / nylon 6 copolymer and copolymers thereof; polyether sulfone, polyphenylene sulfide, polyphenylene Polyether polymers such as oxides; Chlorine or fluorine polymers such as polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, and copolymers thereof; polymethyl acrylate, polyethyl acrylate, polymethyl Acrylic polymers such as methacrylate, polyethyl methacrylate, and polyacrylonitrile and copolymers thereof; styrene polymers such as polystyrene and copolymers thereof; polyimide polymers and copolymers thereof can be used. . Among these, as a thermoplastic resin which comprises the base material 1, a polyethylene terephthalate, a polypropylene, a polyamide-type polymer, a polystyrene, etc. are preferable from a viewpoint of stretch moldability. The substrate 1 may be stretched or unstretched.

The thickness of the substrate 1 is, for example, 10 μm or more and 10 mm or less, and preferably 10 μm or more and 500 μm or less. The substrate 1 may be composed of a plurality of layers.

[First barrier layer 5]
The first barrier layer 5 is one of the layers constituting the barrier layer 2 and includes a polycarboxylic acid polymer and a plasticizer. The polycarboxylic acid-based polymer generates a polyvalent metal compound and a salt contained in the second barrier layer 6 and exhibits a stable gas barrier property. The plasticizer can be added in order to improve the stretchability of the polycarboxylic acid compound. Specifically, by replacing a part of the polycarboxylic acid polymer with a plasticizer, the glass transition temperature of the entire solid content can be lowered and the multilayer sheet 10 can be stretched under a lower temperature condition.

The polycarboxylic acid polymer is not particularly limited as long as it is an existing polycarboxylic acid polymer. The existing polycarboxylic acid polymer is a general term for polymers having two or more carboxy groups in the molecule. Specifically, a homopolymer using α, β-monoethylenically unsaturated carboxylic acid as the polymerizable monomer, and only α, β-monoethylenically unsaturated carboxylic acid as the monomer component, At least two kinds of these copolymers, copolymers of α, β-monoethylenically unsaturated carboxylic acid and other ethylenically unsaturated monomers, and intramolecular such as alginic acid, carboxymethylcellulose, pectin, etc. Examples thereof include acidic polysaccharides having a carboxy group. These polycarboxylic acid polymers can be used alone or as a mixture of at least two kinds of polycarboxylic acid polymers (B).

Here, representative examples of the α, β-monoethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Examples of the ethylenically unsaturated monomer copolymerizable with these include saturated carboxylic acid vinyl esters such as ethylene, propylene, and vinyl acetate, alkyl acrylate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, Styrene and the like are representative. When the polycarboxylic acid polymer is a copolymer of an α, β-monoethylenically unsaturated carboxylic acid and a saturated carboxylic acid vinyl ester such as vinyl acetate, a saturated vinyl The ester moiety can be converted to vinyl alcohol for use.

The polycarboxylic acid polymer is a copolymer of an α, β-monoethylenically unsaturated carboxylic acid and another ethylenically unsaturated monomer, and the multilayer sheet 10 is molded for retort. When used in containers, from the viewpoint of gas barrier properties and resistance to high-temperature steam and hot water, the copolymer composition is such that the α, β-monoethylenically unsaturated carboxylic acid monomer composition is 60 mol% or more. More preferably 80 mol% or more, still more preferably 90 mol% or more, and most preferably 100 mol%, that is, the polycarboxylic acid polymer is an α, β-monoethylenically unsaturated carboxylic acid. A polymer composed only of an acid is preferred. Further, when the polycarboxylic acid polymer is a polymer composed only of α, β-monoethylenically unsaturated carboxylic acid, preferred specific examples thereof are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumar Examples thereof include polymers obtained by polymerization of at least one polymer monomer selected from the group consisting of acid and crotonic acid, and mixtures thereof. More preferably, a homopolymer, a copolymer, and / or a mixture thereof comprising at least one polymerizable monomer selected from acrylic acid, methacrylic acid, and maleic acid can be used. Most preferably, polyacrylic acid, polymethacrylic acid, polymaleic acid, and mixtures thereof can be used. When the polycarboxylic acid polymer is, for example, an acidic polysaccharide other than the polymer of the α, β-monoethylenically unsaturated carboxylic acid monomer, alginic acid can be preferably used.

The polycarboxylic acid polymer is partially mixed with a monovalent metal (alkali metal) or ammonia in advance as long as it does not impair gas barrier properties and resistance to high-temperature steam or hot water when used in a retort molding container. Can be neutralized.

The number average molecular weight of the polycarboxylic acid polymer is not particularly limited. From the viewpoint of film formability, it is preferably in the range of 2,000 to 10,000,000, more preferably 5,000 to 1,000,000.

The polycarboxylic acid-based polymer as a raw material has a dry condition (30 ° C., 0% relative humidity) when formed into a film alone from the viewpoint of gas barrier properties and stability to high-temperature steam and hot water. ) Is preferably 1000 cm ³ (STP) · μm / (m ² · day · MPa) or less, more preferably 500 cm ³ (STP) · μm / (m ² · day · MPa) or less. Yes, and most preferably 100 cm ³ (STP) · μm / (m ² · day · MPa) or less.

Here, the oxygen permeability coefficient can be obtained by the following method, for example. A 10% by mass solution is prepared by dissolving the polycarboxylic acid polymer in a solvent such as water. Next, the prepared solution is coated on a plastic substrate using a bar coater and dried to prepare a coating film on which a polycarboxylic acid polymer having a thickness of 1 μm is formed. The oxygen permeability at 30 ° C. and 0% relative humidity when the obtained coating film is dried is measured. Here, as the plastic substrate, an arbitrary plastic film whose oxygen permeability is known is used. If the oxygen permeability of the resulting polycarboxylic acid polymer coating film is 1/10 or less of the oxygen permeability of the plastic film alone used as the substrate, the measured value of the oxygen permeability Can be regarded as the oxygen permeability of the polycarboxylic acid polymer layer alone. Moreover, since the obtained value is the oxygen permeability of the polycarboxylic acid polymer (B) having a thickness of 1 μm, it can be converted to an oxygen permeability coefficient by multiplying the value by 1 μm.

The plasticizer can be appropriately selected from known plasticizers. Specific examples of the plasticizer include, for example, ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, 1,3-butanediol, 2,3-butanediol, pentamethylene glycol, hexamethylene glycol, diethylene glycol, triethylene. Examples include glycols such as glycol, polyethylene glycol, and polyethylene oxide; sorbitol, mannitol, dulcitol, erythritol, glycerin, lactic acid, and fatty acid. These may be used in a mixture as required. Among these, glycerin, ethylene glycol, polyethylene glycol and the like are preferable from the viewpoints of stretchability and gas barrier properties.

The mixing ratio of the polycarboxylic acid polymer and the plasticizer is preferably 70/30 to 99.9 / 0.1 in terms of mass ratio of the polycarboxylic acid polymer / plasticizer, and 80/20 to 99. / 1 is even more preferable. More preferably, the mass ratio of polycarboxylic acid polymer / plasticizer is 85/15 to 95/5. When the mass ratio of the polycarboxylic acid polymer / plasticizer is in the range of 70/30 to 99.9 / 0.1, both stretchability and gas barrier properties can be achieved.

[Second barrier layer 6]
The second barrier layer 6 is one of the layers constituting the barrier layer 2 and includes a polyvalent metal compound and a resin. The polyvalent metal compound is used to ionically bond with the carboxyl group of the polycarboxylic acid polymer contained in the first barrier layer 5 to improve the gas barrier property. On the other hand, the resin is used as a binder for improving the film formability of the second barrier layer 6.

The polyvalent metal compound is a single polyvalent metal atom having a metal ion valence of 2 or more, and a compound thereof. A divalent metal compound is preferably used as the polyvalent metal compound from the viewpoints of gas barrier properties as a molded container for retort, resistance to high-temperature steam and hot water, and manufacturability. Moreover, on the basis of the sum of the first barrier layer 5 and the second barrier layer 6, the chemical equivalent of the polyvalent metal in the sum of the polyvalent metal compounds relative to the sum of the carboxy groups contained in those layers is 0.2 or more. Further, it is preferably 0.5 chemical equivalent or more and 10 chemical equivalents or less. Furthermore, in addition to the above viewpoints, from the viewpoint of film formability and transparency, it is more preferably in a range of 0.8 chemical equivalents or more and 5 chemical equivalents or less.

Specific examples of the polyvalent metal include alkaline earth metals such as beryllium, magnesium and calcium, transition metals such as titanium, zirconia, chromium, manganese, iron, cobalt, nickel, copper and zinc, and aluminum. . Specific examples of the polyvalent metal compound include oxides, hydroxides, carbonates, organic acid salts, inorganic acid salts of the above polyvalent metals, ammonium complexes of polyvalent metals, and second to fourth grades of polyvalent metals. Examples include amine complexes and carbonates and organic acid salts of these complexes. Organic salts include acetate, oxalate, citrate, lactate, phosphate, phosphite, hypophosphite, stearate, monoethylenically unsaturated carboxylate, etc. It is done. Examples of inorganic acid salts include chlorides, sulfates and nitrates. Other than that, an alkyl alkoxide of a polyvalent metal can be used.

The form of the polyvalent metal compound is not particularly limited. However, from the viewpoint of transparency of the multilayer sheet 10, the polyvalent metal compound is preferably granular and has a smaller particle size. In addition, in preparing a coating mixture for producing a multilayer sheet constituting a retort molding container as described later, from the viewpoint of efficiency during preparation and obtaining a more uniform coating mixture, the polyvalent metal compound is It is preferable to be granular and have a small particle size. The average particle size of the polyvalent metal compound is preferably 5 μm or less, more preferably 1 μm or less, and even more preferably 0.1 μm or less.

When the second barrier layer 6 contains a polyvalent metal compound, the odor generated from the contents after the retort treatment can be reduced. As this mechanism, for example, when zinc oxide is used as the polyvalent metal compound, the zinc oxide becomes zinc ions and reacts with sulfur of hydrogen sulfide (H ₂ S) which causes odor generated from the contents. This is considered to adsorb hydrogen sulfide.

The resin is a thermoplastic resin, a thermosetting resin, or the like, and can be suitably used as long as it is a resin used for paints. Specifically, alkyd resin, amino alkyd resin, melamine resin, acrylic resin, nitrified cotton, urethane resin, polyester resin, phenol resin, amino resin, fluorine resin, silicone resin, epoxy resin, vinyl resin, cellulosic resin, natural Resins such as resins can be mentioned. In addition, a hardening | curing agent can be used as needed and well-known resin, such as a melamine resin, polyisocyanate, a polyamine, can be mentioned.

The mixing ratio of the polyvalent metal compound and the resin is preferably 1/100 to 10/1, more preferably 1/10 to 5/1, and even more preferably, by mass ratio. Is 1/5 to 2/1. It exists in this range from a viewpoint of making heat stretch moldability and oxygen gas barrier property compatible.

The barrier layer 2 is formed by laminating the first barrier layer 5 and the second barrier layer 6 on one surface of the substrate 1 via an adhesive layer or an anchor coat layer, or without an adhesive layer or an anchor coat layer. Is provided. The arrangement of the first barrier layer 5 and the second barrier layer 6 is an ionic bond between the carboxy group of the polycarboxylic acid polymer contained in the first barrier layer 5 and the polyvalent metal compound contained in the second barrier layer 6. In order to generate the above, it is preferable that the first barrier layer 5 and the second barrier layer 6 have a layer configuration including at least one unit of the first barrier layer 5 / second barrier layer 6 which are adjacent layer constituent units. Further, the layer constitutional unit in which the first barrier layer 5 and the second barrier layer 6 are adjacent may be a three-layer constitution of the second barrier layer 6 / the first barrier layer 5 / the second barrier layer 6, Conversely, a three-layer configuration of the first barrier layer 5 / second barrier layer 6 / first barrier layer 5 may be used, and a layer configuration including one or more of these is preferable. In particular, since the polyvalent metal compound contained in the second barrier layer 6 develops an adhesive resin layer containing an acid-modified polyolefin, which will be described later, by hydrogen bonding, the second barrier layer 6 is bonded to the adhesive resin layer 4. It is preferable that the layers are stacked in contact with each other.

The thickness of the first barrier layer 5 before stretch molding is such that the chemical equivalent of the polyvalent metal in the total of the polyvalent metal compound relative to the total of the carboxy groups of the polycarboxylic acid polymer is 0.2 or more. The thickness of the first barrier layer 5 is not less than 0.05 μm and not more than 100 μm, more preferably not less than 0.1 μm and not more than 10 μm in order to ensure good oxygen gas barrier properties. More preferably, it is 0.2 μm or more and 5 μm or less. When the first barrier layer 5 is 0.05 μm or more, stretchability can be exhibited when the first barrier layer 5 is laminated with the second barrier layer 6. Moreover, when the 1st barrier layer 5 is 100 micrometers or less, it becomes possible to maintain high productivity. Further, the thickness of the second barrier layer 6 before being stretch-molded is 0.05 μm or more and 100 μm or less, more preferably 0.1 μm or more, in order to ensure good oxygen gas barrier properties and stretch moldability. It is 10 μm or less, more preferably 0.2 μm or more and 5 μm or less.

[Polyolefin layer 3]
The polyolefin layer 3 is a layer provided on the surface of the barrier layer 2. The polyolefin layer 3 imparts wear resistance, gloss, heat sealability, strength, moisture resistance, and the like to the multilayer sheet 10. As the resin used for the polyolefin layer 3, among the thermoplastic resins used for the substrate 1, a polyolefin resin can be used. For example, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, poly Polyolefin polymers such as 4-methylpentene and cyclic polyolefin, copolymers thereof, and acid-modified products thereof can be used, and polyethylene, polypropylene, and the like are preferably used.

The thickness of the polyolefin layer 3 before being stretch-molded is appropriately determined depending on the thickness of the molded container to be stretch-molded. For example, the thickness is preferably 1 μm or more and 1000 μm or less, and more preferably 5 μm or more and 500 μm or less. More preferably, it is 5 μm or more and 300 μm or less. In addition, the thickness of the polyolefin layer 3 is good also as 1 mm or more according to the specification of a product. The polyolefin layer 3 is attached to the surface of the barrier layer 2 by an adhesive resin layer 4 described later.

[Adhesive resin layer 4]
The adhesive resin layer 4 is an adhesive resin layer for bonding the thermoplastic barrier film 7 to the polyolefin layer 3 without using an adhesive for dry lamination. The adhesive resin layer 4 is formed, for example, by using an acid-modified polyolefin resin such as acid-modified polyethylene or polypropylene as a base resin and mixing a resin modifier such as an α-olefin copolymer. By mixing such a resin modifier, the adhesive resin layer 4 can impart flexibility while maintaining a melting point that can be tolerated even if retorting or the like is performed.

The adhesive resin layer 4 is preferably a graft-modified polyolefin obtained by graft-modifying or copolymerizing at least one polymerizable ethylenically unsaturated carboxylic acid or a derivative thereof with a polyolefin resin before modification. In this case, the functional group imparted to the polyolefin can be bonded by hydrogen bonding with the metal compound contained in the surface layer of the thermoplastic barrier film 7. Examples of the ethylenically unsaturated carboxylic acid or a derivative thereof that is graft-modified or copolymerized with the polyolefin resin before modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, and maleic anhydride. More preferably, maleic anhydride can be used, but these can be used alone or in combination of two or more.

The thickness of the adhesive resin layer 4 before being stretch-molded is not particularly limited as long as it satisfies the function as an adhesive layer, but is, for example, 1 μm or more and 50 μm or less. When the thickness of the adhesive resin layer 4 is 1 μm or more, the thermoplastic barrier film 7 can be sufficiently adhered to the polyolefin layer 3, and peeling of both can be suppressed. Moreover, when the thickness of the adhesive resin layer 4 is 50 μm or less, the adhesive resin layer 4 can be prevented from being unnecessarily thick.

The melt flow rate (MFR) of the resin composition constituting the adhesive resin layer 4 is preferably 3 g / 10 min or more and 10 g / 10 min or less. When the multilayer sheet is formed as a container by being 3 g / 10 min or more, the adhesive resin layer 4 itself or the surface layer of the thermoplastic barrier film 7 is destroyed due to stress or the like, and as a result, the adhesive resin layer 4 and It can suppress that the adhesive strength between the thermoplastic barrier films 7 weakens. On the other hand, by being 10 g / 10 minutes or less, the adhesive resin layer 4 is prevented from being deformed by stress during molding, and in particular, thermoplasticity due to the flow of the adhesive resin layer 4 by hot water treatment such as retort. The wrinkles and peeling of the barrier film 7 can be suppressed. In this regard, when considering the heat resistance in the retort treatment, the base of the resin composition constituting the adhesive resin layer 4 is preferably polypropylene. there is a possibility. On the other hand, polyethylene is more flexible than polypropylene, but its melting point is as low as about 120 ° C., which limits the conditions for retorting. Therefore, as described above, as the adhesive resin composition, for example, it is preferable to use a mixture of polypropylene and a resin modifier such as an α-olefin copolymer. Thereby, a softness | flexibility can be provided, maintaining the melting | fusing point which can endure a retort process. In addition, if satisfy | filling these functions, the resin composition which comprises the adhesive resin layer 4 may consist of another material. Further, these MFRs are obtained by measuring the fluidity of the resin composition at 230 ° C. based on JIS K 7210-1999.

Next, a method for producing the multilayer sheet 10 using the multilayer extruder 20 will be described with reference to FIG. FIG. 2 is a diagram schematically showing a process for manufacturing the multilayer sheet shown in FIG.

First, in order to form the first barrier layer 5 on the substrate 1 such as a PET film, a coating liquid containing a polycarboxylic acid polymer and a plasticizer is prepared. For example, in this preparation step, when polyacrylic acid (hereinafter referred to as “PAA”) is used as the polycarboxylic acid polymer, PAA is diluted with distilled water to prepare a 5 mass% aqueous solution of PAA. A coating solution (PAA / glycerin mixture) for forming the first barrier layer 5 by mixing and stirring 10 parts by mass of a 5% by mass aqueous solution of glycerin as a plasticizer with respect to the obtained PAA aqueous solution, for example, 90 parts by mass. Aqueous solution) is prepared. Next, as shown in FIG. 2 (a), the obtained PAA / glycerin mixture aqueous solution is applied to one side of the substrate 1 by a known coating method and dried, whereby the first barrier layer 5 is formed. Form. The drying temperature is between room temperature and 90 ° C., and the drying time is preferably between 10 seconds and 60 minutes.

Next, a coating solution containing a polyvalent metal compound constituting the second barrier layer 6 and a resin is prepared. For example, in this preparation step, 0 to 15 parts by mass of a curing agent is added to 100 parts by mass of a mixed dispersion (mixed solvent: toluene / MEK) of zinc oxide fine particles as a polyvalent metal compound and a polyester resin as a resin. A mixed solution containing a polyvalent metal compound mixed with is prepared. This mixed liquid is applied to the surface of the first barrier layer 5 by a known coating method and dried to form the second barrier layer 6. Conditions similar to the drying temperature and drying time when forming the first barrier layer 5 can be adopted as the drying temperature and drying time.

As a known coating method, for example, a gravure roll coater, a reverse roll coater, a dip coater, or a die coater, a Meyerba, a method of applying with a brush, a method of spraying a suspension or a solution with a spray, etc. Or the method including an immersion method is mentioned. Thus, the thermoplastic barrier film 7 is prepared.

Next, as shown in FIG. 2 (b), a polyolefin resin composition that forms the polyolefin layer 3, such as polypropylene resin, and a resin composition that forms the adhesive resin layer 4, such as acid-modified polyethylene resin, are multilayered. It is put into an extruder (extruder) 20 and melted at a predetermined temperature so that the resin temperature during extrusion is 200 ° C. to 300 ° C. In order to sufficiently draw out the adhesive strength of the adhesive resin, it is preferable to melt at a predetermined temperature so that the resin temperature during extrusion is 280 ° C. to 300 ° C. Then, the prepared thermoplastic barrier film 7 is supplied to the lower side of the multilayer extruder 20 via the roll 21 and the polypropylene resin 23 and the acid-modified polyethylene resin 24 are shared from the T die of the multilayer extruder 20 or the like. An acid-modified polyethylene resin 24, which is an adhesive resin, is extruded and positioned between the polypropylene resin 23 constituting the polyolefin layer 3 and the thermoplastic barrier film 7 to be supplied. The polypropylene resin 23 and the thermoplastic barrier film 7 constituting the layer 3 are attached to each other. Thereafter, these films are laminated via the roller 22 to complete the multilayer sheet 10.

In addition, since adhesive resin is more expensive than polyolefin resin, such as polypropylene resin which comprises the polyolefin layer 3, in order to adjust the thickness of the multilayer sheet 10, it is preferable to adjust thickness with polyolefin resin. For example, in the above, an example using a two-type two-layer multi-layer extruder was shown, but using a three-type three-layer multi-layer extruder, an adhesive resin composition was supplied from one of the two, and the remaining two systems It is also possible to make the polyolefin layer 3 thicker by extruding a polyolefin resin composition.

Here, with reference to FIG. 2 and FIG. 3, a method for producing a multilayer sheet using a conventional dry laminate and a method for producing a multilayer sheet according to this embodiment will be described in comparison. FIG. 3 is a diagram schematically showing a process for producing a conventional multilayer sheet. As shown in FIG. 3, in the conventional method for producing a multilayer sheet, the thermoplastic barrier film 7 is produced by the process shown in FIG. 3A similar to FIG. For example, a polypropylene sheet (PP sheet) 33 is manufactured. Thereafter, the thermoplastic barrier film 7 is bonded to the PP sheet 33 by dry lamination using an adhesive or the like. On the other hand, in the manufacturing method according to the present embodiment, as shown in FIG. 2B, when the polyolefin layer 3 is formed by co-extrusion of the resin 23 and the adhesive resin 24 constituting the polyolefin layer 3. In addition, bonding to the thermoplastic resin film 7 is performed. For this reason, it is possible to increase the processing speed by the amount of dry laminating compared to the conventional case. For example, in the case of dry laminating a thermoplastic barrier film and a PP sheet having a thickness of 0.6 mm, assuming that the line speed is 30 m / min, and if producing 100,000 m per month, the dry laminating time is 60 It takes a little time. If it is the method concerning this embodiment, since this time can be made unnecessary, it becomes possible to raise the productivity of the multilayer sheet 10 dramatically. In addition, as a specification of the product, the polyolefin layer 3 may be required to have a thickness of 1 mm or more. However, in dry lamination, it is difficult to convey and process a sheet of 1 mm or more, and such processing can be performed. The device is also limited. However, according to the co-extrusion method according to the present embodiment, the polyolefin film 3 can be easily made to be 1 mm or more by a sheet film forming machine, so that it is possible to widen the applicable product group. .

Of course, the multilayer sheet 10 thus produced may be stretch-molded to produce a molded container, and an example of the molded container 40 thus produced is shown in FIG. 4 is a cross-sectional view showing an example of a molded container manufactured using the multilayer sheet shown in FIG. A molded container 40 shown in FIG. 4 is used for storing retort food and the like, and includes a main body 41 and a lid 42. Since the molded container 40 is composed of the multilayer sheet 10 described above, even if a retort process such as pressure heating is applied, a high gas barrier property can be maintained.

Further, another example of the container using the multilayer sheet 10 is shown in FIGS. 5 (a) and 5 (b). FIGS. 5A and 5B are cross-sectional views showing an example of a squeeze container according to an embodiment of the present invention. This squeeze container can be formed into a desired container shape by a melt forming method such as a vacuum forming method using the multilayer sheet 10 composed of the polyolefin layer 3 and the thermoplastic barrier film 7.

FIG. 5A shows a squeeze container when the formed multilayer sheets 10 face each other and are bonded together. On the other hand, FIG. 5 (b) shows a squeeze container when a lid 41 produced by laminating a plastic film or the like on the molded multilayer sheet 10 is sealed. In FIG. 5A, the entire surface of the container has rigidity as a sheet forming container, and the contents can be protected. In FIG. 5B, not only as a squeeze container, but also the container can be used like a tray by peeling off the lid 41 during use. And, these squeeze containers according to an embodiment of the present invention, by bonding the polyolefin resin layer and the thermoplastic barrier film with the adhesive resin layer, it is possible to give the container an appropriate rigidity, In addition, the thermoplastic barrier film has a barrier property.

In addition, the thickness of the resin layer including the polyolefin layer 3 and the adhesive resin layer 4 before being stretch-molded can be appropriately determined depending on the thickness of the molded container to be stretch-molded. Is preferably 100 μm or more and 1000 μm or less, and more preferably 200 μm or more and 600 μm or less. By setting it to 600 μm or less, the squeeze property is improved. The total thickness of the multilayer sheet including the thickness of the thermoplastic barrier film is also preferably 650 μm or less.

The present invention is not limited to the above embodiment, and various modifications can be applied. For example, in the above-described embodiment, the manufacturing method using the T die has been described. However, the present invention is not limited to this, and a multilayer sheet may be manufactured using an inflation die or the like. Moreover, although the example using a multilayer extruder was shown as an extruder, it passed twice through a single-layer extruder. Specifically, first, an adhesive resin composition was extruded, and then a polyolefin layer 3 was formed. It is also possible to produce a multilayer sheet by extruding the polyolefin resin composition.

In addition to the layer configuration shown in FIG. 1, for example, as shown in FIG. 6A, the multilayer sheet includes a multilayer sheet 10 a in which a polyolefin layer 3 and an adhesive resin layer 4 are provided on both sides of the multilayer sheet. There may be. The multilayer sheet 10a employs a layer structure including a thermoplastic barrier film 7a having a barrier layer 2a in which the stacking order of the first barrier layer 5 and the second barrier layer 6 is further changed. A multilayer sheet having Moreover, as shown in FIG.6 (b), the multilayer sheet 10b which has the layer structure which replaced the base material 1, and the barrier layer 2 which consists of the 1st barrier layer 5 and the 2nd barrier layer 6 may be sufficient.

Hereinafter, the multilayer sheet according to the present invention will be described in detail by way of examples, but the present invention is not limited to these examples.

[Example 1]
As the base material 1 of the thermoplastic barrier film, easy-formed tefflex (trade name, registered trademark, manufactured by Teijin DuPont Films Ltd.) 25 μm was selected, and a barrier layer was formed by the following method. First, in order to constitute the first barrier layer 5, PAA was diluted with distilled water as a polycarboxylic acid polymer to prepare a 5% by mass aqueous solution of PAA. A coating liquid (PAA / glycerin mixture aqueous solution) for forming the first barrier layer 5 by mixing and stirring 10 parts by mass of a glycerin 5 mass% aqueous solution as a plasticizer with respect to 90 parts by mass of the obtained PAA aqueous solution. Was prepared. Next, as shown in FIG. 2 (a), the obtained PAA / glycerin mixture aqueous solution was applied to one side of the substrate 1 with a gravure roll coater and dried to form the first barrier layer 5. . Next, for forming the second barrier layer 6, an isocyanate system is used with respect to 100 parts by mass of a mixed dispersion (mixed solvent: toluene / MEK) of zinc oxide fine particles as a polyvalent metal compound and a polyester polyol resin as a resin. A mixed solution containing a polyvalent metal compound mixed with 15 parts by mass of the curing agent was prepared. The liquid mixture was applied to the surface of the first barrier layer 5 by a gravure roll coater and dried to form the second barrier layer 6.

Next, Homo PP “E111G (manufactured by Prime Polymer Co., Ltd., trade name), MFR 0.5 g / 10 min” is prepared as the PP resin constituting the polyolefin layer of the multilayer sheet, and modified PP “Admer QF551” is used as the adhesive resin. (Mitsui Chemicals, Inc., “Admer” is a registered trademark), MFR 5.7 g / 10 min ”was prepared. Next, the homo PP “E111G” and the modified PP “Admer QF551” were charged into an extruder (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.) and melted so that the melting temperature during extrusion was 240 ° C.

Next, the already prepared thermoplastic barrier film is fed below the extruder, and the homo PP “E111G” and the modified PP “Admer QF551” are co-extruded with the extruder, and the modified PP “ The fed thermoplastic barrier film was heat laminated so that Admer QF551 ”was positioned between the thermoplastic barrier film and the homo PP. At that time, the number of revolutions of the extruder screw was adjusted so that the film thickness of the homo PP resin was 600 μm and the film thickness of the adhesive resin was 25 μm. The multilayer sheet 10 shown in FIG. 1 was obtained by the above method.

[Example 2]
The multilayer sheet 10 shown in FIG. 1 was used in the same manner as in Example 1 except that modified PP “Admer QB550 (Mitsui Chemicals,“ Admer ”is a registered trademark), MFR 2.8 g / 10 min” was used as the adhesive resin. Got.

[Example 3]
As an adhesive resin, modified PP “Admer QF551 (Mitsui Chemicals, Inc.,“ Admer ”is a registered trademark)” and “Toughmer XM-7070 (Mitsui Chemicals, Inc.,“ Tafmer ”are registered trademarks) MFR 7.0 g / 10 Using a material in which “min” was mixed at a weight ratio of 10%, and the other conditions were the same as in Example 1, the multilayer sheet 10 shown in FIG. 1 was obtained. The average MFR of the mixed adhesive resin composition was 3.2 g / 10 minutes.

[Comparative Example 1]
As a comparative example, a multilayer sheet by dry lamination was produced. Specifically, a thermoplastic barrier film was first produced by the same method as in Example 1. Next, the thermoplastic barrier film and a general-purpose PP sheet having a thickness of 600 μm (manufactured by OJK Corporation) were bonded with a dry laminator (manufactured by Fuji Machine Industry Co., Ltd.) using an adhesive. As the adhesive, “Takelac A626 (manufactured by Mitsui Chemicals)” and “Takenate A-50 (manufactured by Mitsui Chemicals)” were mixed at a weight ratio of 8: 1, and the coating amount after drying was 5 g / m ² . Coated so that. Thus, the multilayer sheet of Comparative Example 1 was obtained.

[Comparative Example 2]
As Comparative Example 2, a multilayer sheet having a layer structure in the order of PP resin / Admer / EVOH resin / Admer / PP resin was produced. Specifically, homo PP “E111G (manufactured by Prime Polymer Co., Ltd., trade name)” as PP resin, modified PP “Admer QF551 (manufactured by Mitsui Chemicals)” as adhesive resin, and Eval “F171B” as EVOH resin. (Manufactured by Kuraray Co., Ltd.) ". These resins were coextruded so that the thickness of the PP resin was 250 μm, the thickness of the adhesive resin was 20 μm, and the thickness of the EVOH resin was 60 μm. Thus, a multilayer sheet of Comparative Example 2 was obtained.

The multilayer sheets of Examples 1 to 3 obtained as described above and the multilayer sheets of Comparative Examples 1 and 2 were heat-softened using a deep drawing type high-speed automatic vacuum packaging machine, vacuum-formed, and 120 mm long × 120 mm wide × A container with a height of 35 mm was obtained. Using the container thus formed, the following tests were conducted.

[Test 1]
The appearance after vacuum formation and after retorting was confirmed in five containers for each example and each comparative example. The retort process was carried out as a single container, and two conditions of 121 ° C. × 30 minutes and 131 ° C. × 30 minutes were performed. The case where wrinkles that can be visually confirmed and the floating of the laminate part occurred was determined to be “impossible”, and other cases were determined to be “good”.

[Test 2]
The oxygen barrier performance of the container before retort treatment and one day after the retort treatment was measured. The retort process was carried out as a single container, and the conditions were 121 ° C. × 1/30.

[Test 3]
The taste sensory test was conducted according to the following procedure. First, the inside of the container was filled with ultrapure water, and a lid made of an aluminum foil and a sealant film was heat-sealed to the container and sealed, and the retort treatment was performed at 121 ° C. for 30 minutes. Next, water was taken out from the container without giving the type of container to five subjects, and the evaluation was requested in the form of comparison with the water filled in the container of Comparative Example 2. A case equal to or greater than that of Comparative Example 2 was determined as “good”, and a case where the taste / odor was inferior to that of Comparative Example 2 was determined as “impossible”.

The results of Test 1 to Test 3 are shown in Table 1 below.

In Comparative Example 1, the sensory test was inferior to the others due to the influence of the adhesive used for the laminate. In Comparative Example 2, the oxygen barrier after the retort treatment was greatly reduced by the retort shock. On the other hand, in Examples 1 to 3 according to the present invention, both the sensory test and the oxygen barrier after the retort treatment gave good results. In particular, by adjusting the MFR of the adhesive resin, the initial appearance and the appearance after the retort treatment were improved.

From the above, if the multilayer sheet according to the present invention is used, it is possible to provide an optimal container as a container for foods and the like that are required to be resistant to moist heat with respect to hot water treatment such as retort and to suppress odor transfer from the container. Was confirmed.

[Example 4]
Next, in Example 1, when the supplied thermoplastic barrier film was extrusion laminated, the screw speed of the extruder was adjusted so that the film thickness of the adhesive resin was 25 μm. In addition, the film thickness of homo PP was similarly adjusted by adjusting the number of rotations of the screw, and four levels were prepared in which the total thickness of the thermoplastic barrier film, adhesive resin, and polypropylene resin was 175 μm, 375 μm, 575 μm, and 757 μm.

[Comparative Example 3]
As Comparative Example 3, a multilayer sheet having a layer structure in the order of PP resin / adhesive resin / EVOH resin / adhesive resin / PP resin was produced. Specifically, homo PP “E111G (manufactured by Prime Polymer Co., Ltd., trade name)” as PP resin, modified PP “Admer QF551 (manufactured by Mitsui Chemicals)” as adhesive resin, and EVAL “F171B” as EVOH resin. (Kuraray Co., Ltd.) "was prepared. The thickness of each layer was designed so that the thickness of the adhesive resin was fixed at 10 μm with respect to the four levels of total film thickness of 200 μm, 400 μm, 600 μm and 800 μm, and the EVOH ratio was 8%. These resins were extruded using an extruder capable of coextrusion of 3 types and 5 layers to obtain a multilayer sheet using EVOH.

Using the multilayer sheets of Example 4 and Comparative Example 3 obtained as described above, a container having a trapezoidal side surface shown in FIG. 7 was obtained by vacuum forming. The opening has a length of the long side 51 of 50 mm, the length of the short side 52 of 30 mm, the bottom has a length of the long side 53 of 50 mm, a length of the short side 54 of 20 mm, and a depth of the container 55. It was 30 mm. The following tests were conducted using the container thus molded.

[Test 4]
The container not filled with the contents was put into a retort process at 121 ° C. for 30 minutes. Next, the oxygen permeability of the container one day after the retort treatment was measured in an environment of 30 ° C. and 70% by the container mocon method.

[Test 5]
The contents were filled with ketchup sauce up to 90% of the full, and using a lid material in which PET 12 μm, aluminum foil 9 μm, and CPP 70 μm were bonded together in this order, they were bonded so as to close the opening of the container by heat sealing. Next, a 5 mm diameter hole was made in the center of the trapezoidal surface surrounded by the short side 52 and the short side 54 of the container to provide a pseudo squeeze mouth. If 5 subjects were able to squeeze out more than 90% of the contents without any difficulty, assuming that they were actually used, the test was passed. When it occurred, the squeeze property was evaluated as rejected.

Table 2 shows the results of Test 4 and Test 5.

The “resin thickness” in Table 2 is the combined thickness of the polypropylene resin and the adhesive resin in Example 4, and in Comparative Example 3, the combined thickness of the polypropylene resin, the adhesive resin, and the EVOH resin. is there.

In Example 4, the value of oxygen permeability was constant without being affected by the resin thickness, and when the resin thickness was 600 μm or less, both squeeze property and barrier property could be achieved. On the other hand, in Comparative Example 3, the oxygen barrier changed depending on the resin thickness, and the barrier property was greatly inferior to the thickness of 800 μm when the thickness was 600 μm or less where the squeeze property was secured.

From the above, it was confirmed that the use of the multilayer sheet according to one embodiment of the present invention makes it possible to obtain a squeeze container having both squeeze characteristics and high barrier characteristics without depending on the thickness of the container. .

The present invention can be applied to multilayer sheets and molded containers used for boil and retort applications, particularly squeeze containers, and methods for producing them.

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Barrier layer, 3 ... Polyolefin layer, 4 ... Adhesive resin layer, 5 ... 1st barrier layer, 6 ... 2nd barrier layer, 7 ... Thermoplastic barrier film, 10, 10a, 10b ... Multilayer Sheet, 20 ... multilayer extruder, 40 ... molded container.

Claims

A multilayer having a thermoplastic barrier film in which a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid polymer and a plasticizer, and a second barrier layer containing a polyvalent metal compound and a resin are laminated. A sheet manufacturing method comprising:
Preparing the thermoplastic barrier film;
Preparing a polyolefin resin composition and an adhesive resin composition;
While supplying the thermoplastic barrier film, the polyolefin resin composition and the polyolefin resin composition so that the adhesive resin composition is located between the layer formed by the polyolefin resin composition and the supplied thermoplastic barrier film Extruding the adhesive resin composition from an extruder;
A method for producing a multilayer sheet comprising:
The adhesive resin composition comprises an acid-modified polyolefin;
The manufacturing method of the multilayer sheet of Claim 1.
The melt flow rate (MFR) of the adhesive resin composition is 3 g / 10 min or more,
The manufacturing method of the multilayer sheet of Claim 1 or 2.
The adhesive resin composition includes an acid-modified polypropylene resin or an acid-modified polyethylene resin, and a resin modifier made of an α-olefin copolymer.
The method for producing a multilayer sheet according to any one of claims 1 to 3.
In the extruding step, the adhesive resin composition is extruded so that the thickness of the adhesive resin composition is 1 μm or more and 50 μm or less,
The method for producing a multilayer sheet according to any one of claims 1 to 4.
The extruder is a multilayer extruder;
In the extruding step, the polyolefin resin composition and the adhesive resin composition are placed so that the adhesive resin composition overlaps a surface of the layer formed by the polyolefin resin composition on the thermoplastic barrier film side. Co-extrusion from the multilayer extruder,
The method for producing a multilayer sheet according to any one of claims 1 to 5.
In the extruding step, extruding the polyolefin resin composition so that a layer of the polyolefin resin composition has a thickness of 1 mm or more,
The method for producing a multilayer sheet according to any one of claims 1 to 6.
A step of producing a multilayer sheet by the method for producing a multilayer sheet according to any one of claims 1 to 7,
Stretching the multilayer sheet to produce a molded container;
A method for manufacturing a molded container.
A multilayer sheet comprising a polyolefin resin layer, and a thermoplastic barrier film attached to one surface of the polyolefin resin layer with an adhesive resin layer,
The thermoplastic barrier film is formed by laminating a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid polymer and a plasticizer, and a second barrier layer containing a polyvalent metal compound and a resin. A film,
A multilayer sheet in which the thermoplastic barrier film is attached to the one surface of the polyolefin resin layer by the adhesive resin layer, and the adhesive resin layer contains an acid-modified polyolefin.
10. A squeeze container formed by molding the multilayer sheet according to claim 9, wherein a total film thickness of the polyolefin resin layer and the adhesive resin is 200 μm to 600 μm.