JP6954281B2 - Multi-layer sheet manufacturing method, molding container manufacturing method, and multi-layer sheet manufacturing method - Google Patents

Description

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

As a retort treatment for long-term storage of foods and the like, the packaging container may be sterilized by heating under pressure. When ethylene vinyl alcohol copolymer (EVOH resin) is used as the gas barrier layer in the packaging container sheet for such applications, the resistance to humidity and hot water is low, so the barrier performance called retort shock is significantly reduced. Occurs. Therefore, Patent Document 1 proposes a thermoplastic barrier film in which a layer made of a mixture of a polycarboxylic acid-based 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 barrier properties by hot water treatment, the retort shock seen in EVOH resin and 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 separately produced, and after both are produced, the thermoplastic barrier film and the sheet are dry-laminated via an adhesive to produce a multilayer sheet. doing. Therefore, the multilayer sheet described in Patent Document 1 has a problem that the production takes time and the productivity is low. Further, when dry laminating is performed, there are restrictions on the manufacturing conditions, and for example, it is difficult to carry and process a sheet of 1 mm or more (the processing machines that can handle it are limited), so a multilayer sheet having a thickness of a predetermined value or more is manufactured. There is also the problem that it is difficult. Further, as one of the packaging containers using such a multilayer sheet, there is a squeeze container. This is a container form in which the required amount of contents is squeezed out by crushing the container, and is suitable as a container for seasonings such as mayonnaise and mustard, and liquid food such as pet food and baby food. Here, since the thickness of the EVOH resin is proportional to the oxygen barrier property, the improvement of the oxygen barrier property and the improvement of the squeeze property (= thinning) are contradictory. Therefore, it is difficult to ensure squeezeability in a high-barrier container aimed at longer-term storage.

Therefore, the present invention provides a method for manufacturing a multi-layer sheet, a method for manufacturing a molded container, and a multi-layer sheet, which are more productive than the conventional ones and can flexibly respond to many different product specifications. The purpose. Further, as another aspect of the present invention, as the use of the multilayer sheet, the high barrier property that does not depend on the thickness of the container and the barrier property does not deteriorate due to the heat sterilization treatment, and the squeeze that can easily squeeze the contents. It is an object of the present invention to provide a squeeze container having both sexes.

The present invention relates to a method for manufacturing a multilayer sheet as one aspect thereof. In the method for producing this multilayer sheet, a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid-based polymer and a plasticizing agent, 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, which comprises a step of preparing a thermoplastic barrier film, a step of preparing a polyolefin resin composition and an adhesive resin composition, and a step of supplying a thermoplastic barrier film. At the same time, the step of extruding the polyolefin resin composition and the adhesive resin composition from the extruder so that the adhesive resin composition is located between the layer formed by the polyolefin resin composition and the supplied thermoplastic barrier film. And have.

In this method for producing a multilayer sheet, in order to attach the thermoplastic barrier film to the layer formed by the polyolefin resin composition as the sheet base material by the adhesive resin composition, the thermoplastic barrier is in the step of extruding. While supplying the film, the polyolefin resin composition and the adhesive resin composition are extruded from the extruder so that the adhesive resin composition is located between the layer formed by the polyolefin resin composition and the thermoplastic barrier film. I am trying to do it. In this case, when the polyolefin resin composition is extruded to form a polyolefin layer, the polyolefin resin composition and the thermoplastic barrier film are also bonded by thermal lamination. Therefore, the polyolefin resin composition is extruded to form the polyolefin layer as in the conventional case. Since it is possible to eliminate the need for the dry lamination step using the adhesive, which has been performed again after the sheet is produced, the production time can be shortened and the productivity of the multilayer sheet can be increased. For example, assuming that the line speed when laminating a thermoplastic barrier film and a polypropylene sheet with a thickness of 0.6 mm by dry laminating is 30 m / min, if 100,000 m per month is produced, at least about 60 by dry laminating alone. It takes time. However, by adopting the manufacturing method according to the present invention, such a dry lamination step can be omitted, so that the time can be significantly shortened and the productivity of the multilayer sheet can be significantly improved. Further, in this method for producing a multilayer sheet, as described above, since thermal lamination is used, it is possible to easily produce a polyolefin layer of 1 mm or more, which is compared with the production method using dry laminate. Therefore, it is possible to flexibly respond to many different product specifications.

In the above method for producing a multilayer sheet, it is preferable that the adhesive resin composition contains an acid-modified polyolefin. In this case, since the functional groups attached to the polyolefin are bonded by hydrogen bonds 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 as the sheet base material are bonded. It is possible to increase the adhesive strength. The adhesive resin composition used here preferably contains a graft-modified polyolefin in which at least one polymerizable ethylenically unsaturated carboxylic acid or a derivative thereof is graft-modified or copolymerized with a polyolefin resin before modification. ..

In the above method for producing a multilayer sheet, the melt flow rate (MFR) of the adhesive resin composition may be 3 g / 10 minutes 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 the molding process.

In the above method for producing a multilayer sheet, the adhesive resin composition preferably contains an acid-modified polypropylene resin or an acid-modified polyethylene resin and a resin modifier composed 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 step of extruding in the above-mentioned method for producing a multilayer sheet, 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 amount of the expensive adhesive resin composition used can be reduced while maintaining the required adhesive strength.

In the above method for producing a multilayer sheet, the extruder is a multilayer extruder, and in the extrusion step, the adhesive resin composition is overlapped with the surface of the layer formed by the polyolefin resin composition on the thermoplastic barrier filler side. It is preferable to co-extrude the polyolefin resin composition and the adhesive resin composition from a multi-layer extruder. In the present 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. The polyolefin resin composition and the adhesive resin composition may be extruded from the extruder so as to be located between the layer and the thermoplastic barrier film, but the polyolefin resin composition and the adhesive resin may be extruded using a multilayer extruder. By co-extruding the composition, the production speed can be increased and the production efficiency can be further increased.

In the step of extruding in the above-mentioned method for producing a multilayer sheet, 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, the portion of the layer formed by the polyolefin resin composition may require a thickness of 1 mm or more, but it is difficult to process by transporting a sheet of 1 mm or more in dry lamination. However, according to the method according to 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 it is possible to broaden the product group that can be supported.

As another aspect, the present invention relates to a method for manufacturing a molded container. This molding container manufacturing method includes a step of manufacturing a multilayer sheet by any of the above-mentioned manufacturing methods of a multilayer sheet, and a step of stretching and molding the multilayer sheet to manufacture a molded container. In this case as well, it is possible to obtain the same effect as the above-described method for manufacturing a multilayer sheet.

Further, the present invention relates to a multilayer sheet as yet 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 by 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-based polymer and a plasticizing agent, and a second barrier layer containing a polyvalent metal compound and a resin. Is a laminated film, a thermoplastic barrier film is attached to one surface of the polyolefin resin layer by an adhesive resin layer, and the adhesive resin layer contains an 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, it has heat and moisture resistance characteristics. It can be an excellent multilayer sheet. Further, since the polyolefin resin layer and the thermoplastic barrier film are bonded by the adhesive resin layer without using an adhesive, a multilayer sheet can be manufactured without using an organic solvent generally contained in the adhesive. It is possible to prevent the residual odor of the organic solvent from being transferred to the contents arranged in the multilayer sheet (or the molding container to be molded after that), for example, foods, etc., and deteriorating the flavor of the contents.

According to the present invention, it is possible to increase the productivity of the multilayer sheet and flexibly respond to 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 shown in FIG. 1, (a) shows the manufacturing process of a thermoplastic barrier film, (b) is the process of heat laminating a thermoplastic barrier film. show. It is a figure which shows typically the process for manufacturing the conventional multilayer sheet, (a) shows the manufacturing process of a thermoplastic barrier film, and (b) shows the manufacturing process of a PP sheet. It is sectional drawing which shows an example of the molding container manufactured by 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 the comparative example of this invention.

Hereinafter, a method for manufacturing 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 duplicate description will be 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 base material 1, a barrier layer 2 provided on one surface of the base material 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 attached 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-based polymer and a plasticizer, and a second barrier layer 6 containing a polyvalent metal compound and a resin. The thermoplastic barrier film 7 is composed of 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 molded into a packaging container or the like, the polyolefin layer 3 side (upper side in the drawing) of the multilayer sheet 10 is the side in contact with the packaging contents, and the base material 1 side (lower side) of the multilayer sheet 10 is the outside of the container. It becomes.

[Base material 1]
The base material 1 is a base material of the thermoplastic barrier film 7, and is composed of a thermoplastic resin. The type of the thermoplastic resin constituting the base material 1 is not particularly limited, but for example, a polyolefin-based polymer such as low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, poly4-methylpentene, and cyclic polyolefin. And their copolymers, and their acid modified products; vinyl acetate-based copolymers such as polyvinyl acetate, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer saponified products, polyvinyl alcohol; polyethylene terephthalate, Aromatic polyester-based polymers such as polybutylene terephthalate and polyethylene naphthalate and their copolymers; aliphatic polyester-based polymers such as polyε-caprolactone, polyhydroxybutyrate and polyhydroxyvariate and their copolymers; Polyamide-based polymers such as nylon 6, nylon 66, nylon 12, nylon 6,66 copolymers, nylon 6,12 copolymers, metaxylene adipamide / nylon 6 copolymers, and copolymers thereof; polyethers. Polyether-based polymers such as sulfone, polyphenylene sulfide, and polyphenylene oxide; chlorine-based or fluorine-based polymers such as polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and vinylidene fluoride, and copolymers thereof; polymethylacrylate, Acrylic polymers such as polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polyacrylonitrile and their copolymers; styrene polymers such as polystyrene and their copolymers; polyimide polymers and their copolymers, etc. , Can be used. Of these, as the thermoplastic resin constituting the base material 1, polyethylene terephthalate, polypropylene, a polyamide polymer, polystyrene and the like are preferable from the viewpoint of stretch moldability. The base material 1 may be stretched or unstretched.

The thickness of the base material 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 base material 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 is composed of a polycarboxylic acid-based polymer and a plasticizer. The polycarboxylic acid-based polymer forms a salt with the multivalent metal compound contained in the second barrier layer 6 to exhibit stable gas barrier properties. The plasticizer can be added to enhance the stretchability of the polycarboxylic acid compound. Specifically, by substituting a part of the polycarboxylic acid-based 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 lower temperature conditions.

The polycarboxylic acid-based polymer is not particularly limited as long as it is an existing polycarboxylic acid-based polymer. The existing polycarboxylic acid-based polymer is a general term for polymers having two or more carboxy groups in the molecule. Specifically, it is composed of a homopolymer using α, β-monoethylene unsaturated carboxylic acid as the polymerizable monomer, and only α, β-monoethylene unsaturated carboxylic acid as the monomer component. At least two of these copolymers, polymers of α, β-monoethylene unsaturated carboxylic acids and other ethylenically unsaturated monomers, and intramolecules such as alginic acid, carboxymethyl cellulose, and pectin. An acidic polymer having a carboxy group in the above can be exemplified. These polycarboxylic acid-based polymers can be used alone or in combination of at least two types of polycarboxylic acid-based polymers (B).

Here, as the α, β-monoethyl unsaturated carboxylic acid, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like are typical. Examples of the ethylenically unsaturated monomer copolymerizable with these include saturated carboxylic acid vinyl esters such as ethylene, propylene and vinyl acetate, alkyl acrylates, vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride. Styrene is a typical example. When the polycarboxylic acid-based polymer is a copolymer of α, β-monoethylene unsaturated carboxylic acid and saturated carboxylic acid vinyl esters such as vinyl acetate, it is further saponified to obtain saturated vinyl carboxylate. The ester moiety can be converted to vinyl alcohol for use.

Further, when the polycarboxylic acid-based polymer is a copolymer of α, β-monoethylene unsaturated carboxylic acid and other ethylenically unsaturated monomers, the multilayer sheet 10 is molded for retort. When used in a container, the copolymer composition thereof is 60 mol% or more of α, β-monoethylene unsaturated carboxylic acid monomer composition from the viewpoint of gas barrier property and resistance to high temperature steam and hot water. It is preferable, more preferably 80 mol% or more, further preferably 90 mol% or more, and most preferably 100 mol%, that is, the polycarboxylic acid-based polymer is an α, β-monoethylene unsaturated carboxylic. It is preferably a polymer consisting only of an acid. Further, when the polycarboxylic acid-based polymer is a polymer consisting only of α, β-monoethylene unsaturated carboxylic acid, suitable specific examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumar. Examples thereof include a polymer obtained by polymerizing at least one polymer monomer selected from the group consisting of acid and crotonic acid, and a mixture thereof. More preferably, a homopolymer, a copolymer, and / or a mixture thereof consisting of 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-based polymer is, for example, an acidic polysaccharide other than the polymer of the α, β-monoethylene unsaturated carboxylic acid monomer, alginic acid can be preferably used.

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

The number average molecular weight of the polycarboxylic acid-based polymer is not particularly limited. From the viewpoint of film moldability, the range is preferably 2,000 or more and 10,000,000 or less, and further preferably 5,000 or more and 1,000,000 or less.

The polycarboxylic acid-based polymer as a raw material has a gas barrier property and is stable against high-temperature steam and hot water. The oxygen permeation coefficient measured in ^{() 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. Most preferably, it is 100 cm ³ (STP) · μm / (m ² · day · MPa) or less.

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

The plasticizer can be appropriately selected from known plasticizers and used. Specific examples of the plasticizer include ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, 1,3-butanediol, 2,3-butanediol, pentamethylene glycol, hexamethylene glycol, diethylene glycol, and triethylene. Glycols such as glycols, polyethylene glycols and polyethylene oxides; sorbitol, mannitol, zulucitol, erythritol, glycerin, lactic acid, fatty acids and the like can be exemplified. These may be used as a mixture, if desired. Among these, glycerin, ethylene glycol, polyethylene glycol and the like are preferable from the viewpoint of stretchability and gas barrier property.

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

[Second barrier layer 6]
The second barrier layer 6 is one of the layers constituting the barrier layer 2, and is composed of a polyvalent metal compound and a resin. The polyvalent metal compound is used for ionic bonding with the carboxyl group of the polycarboxylic acid-based 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-forming property of the second barrier layer 6.

The polyvalent metal compound is a simple substance of a 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 property as a molded container for retort, resistance to high-temperature steam and hot water, and manufacturability. Further, based on the total of the first barrier layer 5 and the second barrier layer 6, the chemical equivalent of the polyvalent metal in the total of the polyvalent metal compounds with respect to the total 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 equivalent or less. Further, in addition to the above viewpoints, from the viewpoint of film moldability and transparency, the range is more preferably 0.8 chemical equivalents or more and 5 chemical equivalents or less.

Specific examples of polyvalent metals 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 of the polyvalent metal, hydroxides, carbonates, organic acid salts, inorganic acid salts, ammonium complexes of the polyvalent metal, and grades 2 to 4 of the polyvalent metal. Examples thereof include amine complexes and carbonates and organic acid salts of these complexes. Examples of organic acid salts include acetates, oxalates, citrates, lactates, phosphates, phosphites, hypophosphates, stearate, monoethylene unsaturated carboxylates and the like. Be done. Examples of the inorganic acid salt include chlorides, sulfates and nitrates. Other examples include alkyl alkoxides, which are multivalent metals.

The form of the polyvalent metal compound is not particularly limited. However, from the viewpoint of the transparency of the multilayer sheet 10, the polyvalent metal compound is preferably granular and has a small particle size. In addition, as will be described later, in preparing a coating mixture for producing a multilayer sheet constituting a molding container for retort, the multivalent metal compound is used from the viewpoint of improving efficiency at the time of preparation and obtaining a more uniform coating mixture. It is preferable that the particle size is granular and the particle size is small. The average particle size of the polyvalent metal compound is preferably 5 μm or less, more preferably 1 μm or less, and further 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, the case of using zinc oxide as the multivalent metal compound, zinc oxide becomes zinc ion, by reacting with the sulfur hydrogen sulfide which causes odor generated from the contents of (H 2 _S) This is thought to be due to the adsorption of hydrogen sulfide.

The resin is a thermoplastic resin, a thermosetting resin, or the like, and any resin used for paints can be preferably used. Specifically, alkyd resin, amino alkyd resin, melamine resin, acrylic resin, nitrified cotton, urethane resin, polyester resin, phenol resin, amino resin, fluororesin, silicone resin, epoxy resin, vinyl resin, cellulose resin, natural Examples thereof include resins such as resins. If necessary, a curing agent can be used, and known resins such as melamine resin, polyisocyanate, and 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 further preferably 1/10 to 5/1 in terms of mass ratio of the polyvalent metal compound / resin. Is 1/5 to 2/1. It is preferable that it is in this range from the viewpoint of achieving both heat-stretch moldability and oxygen gas barrier property.

The barrier layer 2 is laminated with the first barrier layer 5 and the second barrier layer 6 on one surface of the base material 1 via an adhesive layer or an anchor coat layer, or without an adhesive layer or an anchor coat layer. It is provided by. 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. It is preferable that the layer structure includes at least one unit of the first barrier layer 5 / the second barrier layer 6 which is a layer structure unit in which the first barrier layer 5 and the second barrier layer 6 are adjacent to each other. Further, the layer constitutional unit in which the first barrier layer 5 and the second barrier layer 6 are adjacent to each other may have a three-layer structure of a second barrier layer 6 / a first barrier layer 5 / a second barrier layer 6. On the contrary, it may have a three-layer structure of a first barrier layer 5 / a second barrier layer 6 / a first barrier layer 5, and a layer structure containing one or more of these is preferable. In particular, since the polyvalent metal compound contained in the second barrier layer 6 exhibits adhesion by hydrogen bonding to the adhesive resin layer containing the acid-modified polyolefin described later, the second barrier layer 6 is attached to the adhesive resin layer 4. It is preferable that the layers are laminated in a contacting layer structure.

The thickness of the first barrier layer 5 before stretch molding is a condition that the chemical equivalent of the polyvalent metal in the total of the polyvalent metal compounds with respect to the total of the carboxy groups of the polycarboxylic acid-based polymer is 0.2 or more. The thickness is not particularly limited as long as it is below, but in order to ensure good oxygen gas barrier properties, the thickness of the first barrier layer 5 is 0.05 μm or more and 100 μm or less, more preferably 0.1 μm or more and 10 μm or less. Yes, more preferably 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 laminated with the second barrier layer 6. Further, when the first barrier layer 5 is 100 μm or less, high productivity can be maintained. The thickness of the second barrier layer 6 before stretch molding is 0.05 μm or more and 100 μm or less, more preferably 0.1 μm or more, in order to secure 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 abrasion resistance, glossiness, 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 base material 1, a polyolefin resin can be used, for example, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, poly. Polyolefin-based 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 stretch molding is appropriately determined depending on the thickness of the molding container to be stretch-molded. For example, it is preferably 1 μm or more and 1000 μm or less, and more preferably 5 μm or more and 500 μm or less. It is more preferably 5 μm or more and 300 μm or less. The thickness of the polyolefin layer 3 may be 1 mm or more depending on the specifications of the product. The polyolefin layer 3 is attached to the surface of the barrier layer 2 by the 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 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 be imparted with flexibility while maintaining a melting point that can withstand even if a retort treatment or the like is performed.

The adhesive resin layer 4 is preferably a graft-modified polyolefin in which at least one polymerizable ethylenically unsaturated carboxylic acid or a derivative thereof is graft-modified or copolymerized with a polyolefin resin before modification. In this case, the functional group imparted to the polyolefin can be adhered 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 includes 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 stretch molding 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. Further, when the thickness of the adhesive resin layer 4 is 50 μm or less, it is possible to prevent the adhesive resin layer 4 from being unnecessarily thickened.

The melt flow rate (MFR) of the resin composition constituting the adhesive resin layer 4 is preferably 3 g / 10 minutes or more and 10 g / 10 minutes or less. When the multi-layer sheet is formed as a container by 3 g / 10 minutes or more, the adhesive resin layer 4 itself and the surface layer of the thermoplastic barrier film 7 are destroyed by stress or the like, and as a result, the adhesive resin layer 4 and the adhesive resin layer 4 are destroyed. It is possible to prevent the adhesive strength with the thermoplastic barrier film 7 from being weakened. On the other hand, when it is 10 g / 10 minutes or less, the adhesive resin layer 4 is suppressed from being deformed by the stress during molding, and in particular, the thermoplasticity due to the flow of the adhesive resin layer 4 by hot water treatment such as retort. Wrinkles and peeling of the barrier film 7 can be suppressed. In this regard, when considering the heat resistance in the retort treatment, polypropylene is preferable as the base of the resin composition constituting the adhesive resin layer 4, but in general polypropylene flexibility, peeling due to surface layer fracture described above is performed. there is a possibility. On the other hand, polyethylene has higher flexibility than polypropylene, but its melting point is as low as about 120 ° C., which limits the conditions for retort treatment. 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. As a result, flexibility can be imparted while maintaining a melting point that can withstand the retort treatment. The resin composition constituting the adhesive resin layer 4 may be made of another material as long as it satisfies these functions. Further, these MFRs shall be obtained by measuring the fluidity of the resin composition at 230 ° C. based on JIS K 7210-1999.

Next, a method of manufacturing the multilayer sheet 10 by 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 base material 1 such as a PET film, a coating liquid containing a polycarboxylic acid-based 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-based polymer, PAA is diluted with distilled water to prepare a 5% by mass aqueous solution of PAA. A coating liquid (PAA / glycerin mixture) for forming the first barrier layer 5 is mixed with 10 parts by mass of a 5% by mass aqueous solution of glycerin as a plasticizer and stirred with respect to 90 parts by mass of the obtained PAA aqueous solution, for example. Aqueous solution) is prepared. Next, as shown in FIG. 2A, the obtained PAA / glycerin mixture aqueous solution is applied to one side of the base material 1 by a known coating method and dried to form the first barrier layer 5. 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 liquid containing the polyvalent metal compound and the resin constituting the second barrier layer 6 is prepared. For example, in this preparation step, the curing agent is 0 to 15 parts by mass 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 resin as a resin. To prepare a mixed solution containing a polyvalent metal compound mixed with the above. The second barrier layer 6 is formed by applying this mixed solution to the surface of the first barrier layer 5 by a known coating method and drying it. As the drying temperature and the drying time, the same conditions as the drying temperature and the drying time at the time of forming the first barrier layer 5 can be adopted.

As known coating methods, for example, a method of coating with a gravure roll coater, a reverse roll coater, a dip coater, a die coater, a Mayaba, a brush, or the like, a method of spraying a suspension or a solution with a spray or the like, Alternatively, a method including a dipping method can be mentioned. As described above, the thermoplastic barrier film 7 is prepared.

Next, as shown in FIG. 2B, a polyolefin resin composition forming the polyolefin layer 3, for example, a polypropylene resin, and a resin composition forming the adhesive resin layer 4, for example, an acid-modified polyethylene resin are laminated. It is put into an extruder (extruder) 20 and melted at a predetermined temperature so that the resin temperature at the time of extrusion becomes 200 ° C. to 300 ° C. In order to sufficiently draw out the adhesive force of the adhesive resin, it is preferable to melt the resin at a predetermined temperature so that the resin temperature at the time of extrusion is 280 ° C to 300 ° C. Then, the thermoplastic barrier film 7 prepared in advance is supplied below 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 extruded adhesive resin, is positioned between the polypropylene resin 23 constituting the polyolefin layer 3 and the supplied thermoplastic barrier film 7, and the adhesive resin 24 causes the polyolefin. The polypropylene resin 23 constituting the layer 3 and the thermoplastic barrier film 7 are attached to each other. After that, these films are laminated via the rollers 22, and the multilayer sheet 10 is completed.

Since the adhesive resin is more expensive than the polyolefin resin such as the polypropylene resin constituting the polyolefin layer 3, it is preferable to adjust the thickness with the polyolefin resin in order to adjust the thickness of the multilayer sheet 10. For example, in the above example, an example using a two-kind two-layer multi-layer extruder was shown, but an adhesive resin composition was obtained from one of the three-kind three-layer multi-layer extruders, and the remaining two lines were used. It is also possible to extrude the polyolefin resin composition from the material to make the polyolefin layer 3 thicker.

Here, with reference to FIGS. 2 and 3, a method of manufacturing a multilayer sheet using a conventional dry laminate and a method of manufacturing a multilayer sheet according to the present embodiment will be described in comparison with each other. FIG. 3 is a diagram schematically showing a process for manufacturing 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 same process shown in FIG. 3 (a) as in FIG. 2 (a), and corresponds to the polyolefin layer 3. For example, a polypropylene sheet (PP sheet) 33 is manufactured. Then, after that, the thermoplastic barrier film 7 is attached to the PP sheet 33 by dry lamination using an adhesive or the like. On the other hand, in the production method according to the present embodiment, as shown in FIG. 2B, when the resin 23 constituting the polyolefin layer 3 and the adhesive resin 24 are coextruded to form the polyolefin layer 3. At the same time, it is bonded to the thermoplastic resin film 7. Therefore, as compared with the conventional case, the processing speed can be increased by the amount of the dry laminating process. 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, if 100,000 m per month is produced, the dry laminating processing time alone is 60. It takes a little less than time. According to the method according to the present embodiment, this time can be eliminated, so that the productivity of the multilayer sheet 10 can be dramatically increased. Further, as a product specification, it may be necessary to make the polyolefin layer 3 having a thickness of 1 mm or more, but it is difficult to transport and process a sheet of 1 mm or more by dry laminating, and such processing is possible. The equipment is also limited. However, according to the coextrusion method according to the present embodiment, the polyolefin layer 3 can be easily made to 1 mm or more by the sheet film forming machine, so that the applicable product group can be widened. ..

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. FIG. 4 is a cross-sectional view showing an example of a molded container manufactured by using the multilayer sheet shown in FIG. The molded container 40 shown in FIG. 4 is used for storing retort foods and the like, and includes a main body 41 and a lid 42. Since the molding container 40 is composed of the above-mentioned multilayer sheet 10, even if a retort treatment such as pressure heating is applied, a high gas barrier property can be maintained.

Further, other examples of the container using the multilayer sheet 10 are shown in FIGS. 5 (a) and 5 (b). 5 (a) and 5 (b) 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 molding method such as a vacuum forming method using a multilayer sheet 10 composed of a polyolefin layer 3 and a thermoplastic barrier film 7.

FIG. 5A shows a squeeze container in which the molded multilayer sheets 10 are faced to each other and bonded together. On the other hand, FIG. 5B shows a squeeze container when a lid material 41 produced by laminating a plastic film or the like on a molded multilayer sheet 10 is sealed. In FIG. 5A, the entire surface of the container has rigidity as a sheet-molded container, and the contents can be protected. In FIG. 5B, the container can be used not only as a squeeze container but also as a tray by peeling off the lid material 41 at the time of use. Then, in these squeeze containers according to the embodiment of the present invention, by laminating the polyolefin resin layer and the thermoplastic barrier film with the adhesive resin layer, it becomes possible to give the container appropriate rigidity. Moreover, the thermoplastic barrier film provides a barrier property.

The thickness of the resin layer in which the polyolefin layer 3 and the adhesive resin layer 4 are combined before being stretch-molded is appropriately determined by the thickness of the molding container to be stretch-molded, but is a container having squeeze property. It 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 the thickness 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 embodiment, the manufacturing method using the T die has been described, but the present invention is not limited to this, and the multilayer sheet may be manufactured using an inflation die or the like. Further, although an example in which a multi-layer extruder is used as the extruder is shown, the adhesive resin composition is first extruded by passing it through a single-layer extruder twice, and then the polyolefin layer 3 is formed. It is also possible to extrude the polyolefin resin composition to be produced to produce a multilayer sheet.

Further, as the configuration of the multilayer sheet, in addition to the layer configuration shown in FIG. 1, for example, as shown in FIG. 6A, the multilayer sheet 10a in which the polyolefin layer 3 and the adhesive resin layer 4 are provided on both sides of the multilayer sheet. There may be. The multilayer sheet 10a further adopts 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 changed. Such a layer structure is adopted. It may be a multilayer sheet having. Further, as shown in FIG. 6B, the multilayer sheet 10b may have a layer structure in which the base material 1 and the barrier layer 2 composed of the first barrier layer 5 and the second barrier layer 6 are replaced.

Hereinafter, the multilayer sheet according to the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
Easy-molding Teflex (manufactured by Teijin DuPont Film Co., Ltd., trade name, registered trademark) 25 μm was selected as the base base material 1 of the thermoplastic barrier film, and the barrier layer was formed by the following method. First, in order to form the first barrier layer 5, PAA was diluted with distilled water as a polycarboxylic acid-based polymer to prepare a 5% by mass aqueous solution of PAA. 10 parts by mass of glycerin 5% by mass as a plasticizer is mixed with 90 parts by mass of the obtained PAA aqueous solution and stirred to form a first barrier layer 5 (PAA / glycerin mixture aqueous solution). Was prepared. Next, as shown in FIG. 2A, the obtained PAA / glycerin mixture aqueous solution was applied to one side of the base material 1 with a gravure roll coater and dried to form the first barrier layer 5. .. Next, in order to form the second barrier layer 6, an isocyanate system is used with respect to 100 parts by mass of a mixed dispersion liquid (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 a curing agent was prepared. This mixed solution was applied to the surface of the first barrier layer 5 with a gravure roll coater and dried to form the second barrier layer 6.

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

Next, the already prepared thermoplastic barrier film is fed under the extruder, and the homo-PP "E111G" and the modified PP "Admer QF551" are co-extruded with the extruder, and the modified PP "adhesive resin" is used. The fed thermoplastic barrier film was heat-laminated so that the "Admer QF551" was located between the thermoplastic barrier film and the homo-PP. At that time, the rotation speed of the screw of the extruder 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. By the above method, the multilayer sheet 10 shown in FIG. 1 was obtained.

[Example 2]
The multilayer sheet 10 shown in FIG. 1 is the same as in Example 1 except that the modified PP "Admer QB550 (Mitsui Chemicals, Inc.," Admer "is a registered trademark) and MFR 2.8 g / 10 minutes" are used as the adhesive resin. Got

[Example 3]
As an adhesive resin, "Toughmer XM-7070 (Mitsui Chemicals, Inc.," Toughmer "is a registered trademark) MFR 7.0 g / 10 against the modified PP" Admer QF551 (Mitsui Chemicals, Inc., "Admer" is a registered trademark) " A multilayer sheet 10 shown in FIG. 1 was obtained in the same manner as in Example 1 using a material in which "minutes" were mixed at a weight ratio of 10%. The average MFR of this mixed adhesive resin composition was 3.2 g / 10 minutes.

[Comparative Example 1]
As a comparative example, a multi-layer sheet by dry lamination was produced. Specifically, first, a thermoplastic barrier film was prepared by the same method as in Example 1. Next, the thermoplastic barrier film and a general-purpose PP sheet (manufactured by OJK Co., Ltd.) having a thickness of 600 μm were bonded together with a dry laminator (manufactured by Fuji Kikai Kogyo Co., Ltd.) using an adhesive. As for the adhesive, "Takelac A626 (manufactured by Mitsui Chemicals, Inc.)" and "Takenate A-50 (manufactured by Mitsui Chemicals, Inc.)" are mixed at a weight ratio of 8: 1, and the coating amount after drying is 5 g / m ² . I painted it so that it would be. From the above, 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, first, the homo PP "E111G (manufactured by Prime Polymer Co., Ltd., trade name)" as the PP resin, the modified PP "Admer QF551 (manufactured by Mitsui Chemicals, Inc.)" as the adhesive resin, and the EVAL "F171B" as the EVOH resin. (Made by Kuraray Co., Ltd.) ”was prepared. Then, these resins were co-extruded so that the film thickness of the PP resin was 250 μm, the film thickness of the adhesive resin was 20 μm, and the film thickness of the EVOH resin was 60 μm. From the above, the multilayer sheet of Comparative Example 2 was obtained.

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

[Test 1]
The appearance after vacuum formation and after retort treatment was confirmed in 5 containers for each Example and each Comparative Example. The retort treatment was carried out under the conditions of 121 ° C. × 30 minutes and 131 ° C. × 30 minutes by putting the container alone. When wrinkles or floating of the laminated part that can be visually confirmed occurred, it was evaluated as "impossible", and in other cases, it was evaluated as "good".

[Test 2]
The oxygen barrier performance of the container before the retort treatment and one day after the retort treatment was measured. The retort treatment was carried out by putting the container alone and setting the condition to 121 ° C. × 1/30.

[Test 3]
A taste sensory test was performed according to the following procedure. First, the inside of the container was filled with ultrapure water, a lid material made of aluminum foil and a sealant film was heat-sealed into the container, sealed, and put into a retort treatment at 121 ° C. for 30 minutes. Next, five subjects were given water taken out of the container without telling the type of the container, and the evaluation was requested in the form of comparison with the water filled in the container of Comparative Example 2. When it was equal to or higher than that of Comparative Example 2, it was evaluated as "good", and when it was inferior in taste / odor to Comparative Example 2, it was evaluated as "impossible".

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

In Comparative Example 1, the result was inferior to the others in the sensory test due to the influence of the adhesive used for laminating. Further, in Comparative Example 2, the retort shock resulted in a significant decrease in the oxygen barrier after the retort treatment. 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 appearance at the initial stage and after the retort treatment was improved.

Based on the above, by using the multilayer sheet according to the present invention, it is possible to provide an optimum container as a container for foods and the like, which is required to have moisture and heat resistance to hot water treatment such as retort pouch and suppress odor transfer from the container. Was confirmed.

[Example 4]
Next, in Example 1, when the fed thermoplastic barrier film was extruded and laminated, the rotation speed of the extruder screw was adjusted so that the film thickness of the adhesive resin was 25 μm. Further, the thickness of the homo-PP was adjusted by adjusting the number of rotations of the screw to prepare four levels in which the total thickness of the thermoplastic barrier film, the adhesive resin, and the 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, first, the homo PP "E111G (manufactured by Prime Polymer Co., Ltd., trade name)" as the PP resin, the modified PP "Admer QF551 (manufactured by Mitsui Chemicals, Inc.)" as the adhesive resin, and the EVAL "F171B" as the EVOH resin. (Kuraray Co., Ltd.) ”was prepared. Then, the thickness of the adhesive resin was fixed at 10 μm with respect to the four levels of the total film thickness of 200 μm, 400 μm, 600 μm, and 800 μm, and the thickness of each layer was designed so that the ratio of EVOH was 8%. These resins were extruded using an extruder capable of coextruding 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 a vacuum forming method. The opening has a long side 51 of 50 mm, a short side 52 of 30 mm, and a bottom surface has a long side 53 of 50 mm, a short side 54 of 20 mm, and a container depth of 55. It was set to 30 mm. The following tests were performed using the container thus molded.

[Test 4]
A container unfilled with contents was put into a retort treatment at 121 ° C. for 30 minutes. Next, the oxygen permeability of the container one day after the retort treatment was measured by the container Mocon method in an environment of 30 ° C. and 70%.

[Test 5]
Ketchup sauce was filled up to 90% of the contents, and PET 12 μm, aluminum foil 9 μm, and CPP 70 μm were bonded in this order using a lid material that was heat-sealed so as to close the opening of the container. Next, a hole having a diameter of 5 mm was made in the center of the trapezoidal surface surrounded by the short side 52 and the short side 54 of the container, and a pseudo squeezing port was provided. We asked 5 subjects to squeeze out assuming actual use, and passed the case where all 5 subjects could squeeze out 90% or more of the contents without difficulty, and the container was hard and 10% or more of the contents remained. The squeeze property was evaluated by rejecting the case where it occurred.

The results of Test 4 and Test 5 are shown in Table 2.

なお、表２における「樹脂厚み」は、実施例４では、ポリプロピレン樹脂と接着性樹脂とを合わせた厚みであり、比較例３では、ポリプロピレン樹脂と接着性樹脂とＥＶＯＨ樹脂とを合わせた厚みである。

The "resin thickness" in Table 2 is the total thickness of the polypropylene resin and the adhesive resin in Example 4, and the total thickness of the polypropylene resin, the adhesive resin, and the EVOH resin in Comparative Example 3. be.

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 when the thickness was 600 μm or less where the squeeze property could be ensured, the barrier property was significantly inferior to that of the 800 μm thickness.

From the above, it was confirmed that by using the multilayer sheet according to one embodiment of the present invention, the barrier property does not depend on the thickness of the container, and it is possible to obtain a squeeze container having both squeeze property and high barrier property. ..

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

1 ... Base material, 2 ... Barrier layer, 3 ... Polyolefin layer, 4 ... Adhesive resin layer, 5 ... First barrier layer, 6 ... Second barrier layer, 7 ... Thermoplastic barrier film, 10, 10a, 10b ... Multilayer Sheet, 20 ... Multi-layer extruder, 40 ... Molded container.

Claims (10)

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. It ’s a sheet manufacturing method.
The step of preparing the thermoplastic barrier film and
The process of preparing the polyolefin resin composition and the adhesive resin composition, and
The polyolefin resin composition and the polyolefin resin composition are supplied so that the adhesive resin composition is located between the layer formed by the polyolefin resin composition and the supplied thermoplastic barrier film while supplying the thermoplastic barrier film. The step of extruding the adhesive resin composition from the extruder and
Equipped with a,
The melt flow rate (MFR) of the adhesive resin composition is 3 g / 10 minutes or more.
Manufacturing method of multi-layer sheet. The adhesive resin composition comprises an acid-modified polyolefin.
The method for manufacturing a multilayer sheet according to claim 1. The melt flow rate (MFR) of the adhesive resin composition is 10 g / 10 minutes or less.
The method for producing a multilayer sheet according to claim 1 or 2. The adhesive resin composition contains an acid-modified polypropylene resin or an acid-modified polyethylene resin and a resin modifier composed of an α-olefin copolymer.
The method for manufacturing a multilayer sheet according to any one of claims 1 to 3. In the step of extruding, 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 multi-layer extruder.
In the extrusion step, the polyolefin resin composition and the adhesive resin composition are mixed so that the adhesive resin composition overlaps the surface of the layer formed by the polyolefin resin composition on the thermoplastic barrier film side. Coextruding from the multilayer extruder,
The method for manufacturing a multilayer sheet according to any one of claims 1 to 5. In the extrusion step, the polyolefin resin composition is extruded so that the layer made of the polyolefin resin composition has a thickness of 1 mm or more.
The method for manufacturing a multilayer sheet according to any one of claims 1 to 6. A step of manufacturing a multilayer sheet by the method for manufacturing a multilayer sheet according to any one of claims 1 to 7.
A step of stretching and molding the multilayer sheet to prepare a molded container, and
A method for manufacturing a molded container. A multilayer sheet containing a polyolefin resin layer and a thermoplastic barrier film attached to one surface of the polyolefin resin layer by an adhesive resin layer.
In the thermoplastic barrier film, a base material containing a thermoplastic resin, a first barrier layer containing a polycarboxylic acid-based polymer and a plasticizer, and a second barrier layer containing a polyvalent metal compound and a resin are laminated. It's a film
The heat by the thermoplastic barrier film the adhesive resin layer is adhered to the one surface of the polyolefin resin layer, viewed containing the adhesive resin layer is an acid-modified polyolefin,
A multilayer sheet in which the melt flow rate (MFR) of the resin composition constituting the adhesive resin layer is 3 g / 10 minutes or more. The squeeze container according to claim 9, wherein the thickness of the polyolefin resin layer and the adhesive resin layer combined is 200 μm to 600 μm.

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