WO2003070581A1 - Laminated material for paper containers, and paper container for liquid - Google Patents

Abstract

The invention relates to a laminated material for paper containers used mainly for holding liquid food that is retorted, and to a paper container for liquid. This laminated material (8) for paper containers has a thermoplastic resin layer (3), barrier layer (5), and a first sealant layer (6) that are successively laminated on one surface of a paper layer (1). The paper layer (1) has a resin impregnated in or coated on a fiber structure. This ensures that even if moisture is absorbed in the paper layer (1) during retorting, the strength required of a container can be retained. Further, the moisture absorbed by the paper layer rapidly evaporates through a plurality of through-holes (30h) formed in the paper surface or a second sealant layer (30) except for the ear portion, until the paper surface dries.

Description

 Specification

Laminated materials for paper containers and liquid paper containers

Technical field

 TECHNICAL FIELD The present invention relates to a laminated material for a paper container and a liquid paper container, which can be subjected to a heat sterilization treatment and has a hot water-resistant property based on paper having excellent gas barrier properties and steam barrier properties.

Background art

 Retort containers (metal cans, glass bottle containers) or retort pouches (three-side seal pouches, four-side seal bouches, standing pouches, etc.) are widely used in a wide range of fields as food containers that can be distributed at room temperature for a long period of time. I have.

 However, in recent years, environmental issues have been emphasized, and containers and packaging materials are required to be easily disposable, and demand for easy incineration and recycling is increasing.

 However, retort containers, both metal cans and glass bottle containers, are poorly disposable. Furthermore, in addition to the lack of easy disposal, there are also problems such as heavy weight and easy cutting.

 Although retort bouches are easy to dispose of, they are more difficult to transport and store than box-shaped bags because they are bag-shaped.

 In recent years, the need for ecologically compatible paper containers that can be retorted has increased significantly.

Here, a paper sheet using a laminated sheet in which the paperboard and the gas barrier layer are sandwiched between the inner and outer surface layers with a moisture-proof thermoplastic resin layer of polyethylene, polypropylene, polyethylene terephthalate, or the like. Vessels are known.

 In this paper container, a thermoplastic resin layer is laminated on the surface, thereby avoiding direct contact of the paperboard with water or moisture from the surface. However, in this paper container, when heat treatment such as retort treatment using hot water is performed, water is absorbed into the paperboard from the end face of the laminated material.

 Even if the container is cooled after the heat treatment, the water absorbed during the retort treatment cannot be evaporated and remains on the paperboard. As a result, there is a problem in that the interlayer strength, rigidity, etc. of the paperboard are reduced, and the strength of the packaging container is reduced.

 In order to solve the problem of the paper container as described above, the present inventors have replaced paperboard with a resin selected from silane-based resin, melamine-based resin, isocyanate-based resin, and acrylic-based resin. An attempt was made to use a hot-water-treated paper impregnated in the paper. Specifically, a laminated material was formed by combining the heat-resistant paper with a barrier layer and a transparent layer via an adhesive or a low-density polyethylene resin. Next, we tried a method of forming this laminated material into a paper container and retorting.

 However, although this method enables retort treatment, it has a problem that moisture absorbed during retort treatment is difficult to evaporate due to a thermoplastic resin layer on the surface.

 An object of the present invention is to provide a laminated material for a paper container and a liquid paper container which have good drying properties after retorting and can be retorted.

Disclosure of the invention In order to achieve the above object, a laminated material for a paper container and a liquid paper container of the present invention are configured as follows.

 (1) The laminated material for a paper container of the present invention is a laminated material for a paper container in which a thermoplastic resin layer, a barrier layer, and a first sealant layer are sequentially laminated on one surface of a paper layer. Is a fiber structure composed of a composite material of paper and pulp fiber, impregnated or coated with any one of an isocyanate resin, a polypropylene resin, a polyethylene resin, and a polyester resin. It is formed using base paper.

 (2) The laminated material for a paper container of the present invention in the configuration of (1), may include a second sealant layer having a plurality of through holes formed on the other surface of the paper layer.

 (3) In the laminated material for a paper container of the present invention, in the configuration of (2), the diameter of the through hole is 2 mmφ or less as the second sealant layer, and the through hole is formed. The density may be 1 or more per lcm 2.

 (4) The liquid paper container of the present invention is produced using the paper container laminate material of (2) or (3), and the second sealant layer is disposed outside the container.

 In other words, the liquid paper container of the present invention is manufactured using the paper container laminate material according to any one of (1) to (3), and the first sealant layer is disposed inside the container.

(5) The liquid paper container of the present invention is manufactured by using the paper container laminate material according to any one of (1) to (4), and starts from the first side of the rectangle formed from the paper container laminate material. Of the fourth side, each other A rectangular cylindrical body formed by bonding the ends of predetermined first and second sides facing each other to each other, and a first sealant of the end of the third side A band-shaped first seal portion formed by hermetically sealing the layers with each other, and a band-shaped first seal portion formed by hermetically sealing each of the first sealant layers at the end of the fourth side. A second seal portion, two substantially triangular first ear plates bent at both ends of the first seal portion, and two substantially triangular second second plates bent at both ends of the second seal portion. An ear plate may be provided.

 In other words, the liquid paper container of the present invention comprises a front plate, a rear plate, a side plate, a top plate, and a bottom plate portion formed on any one of the laminated materials for a paper container according to any one of (1) to (4), The rear plate ends may be adhered to each other to form a cylindrical body, and the upper and lower parts may be hermetically sealed with a band.

 (6) In the liquid paper container according to the present invention, in the configuration of (5), when one of the ends of the first side and the second side is located inside the container, the inside of the container. May have a skived portion formed on the paper layer.

 In other words, in the liquid paper container of the present invention, in the configuration of (5), the paper layer corresponding to the glue margin panel portion at the end of the rear plate forming the cylindrical body is subjected to skive hemming. Thereafter, the glue margin of the skived portion may be adhered to the end of the other rear plate to seal the cylindrical body.

(7) In the liquid paper container according to the present invention, in the configuration according to (5) or (6), the first and second seal portions may have outer surfaces outside the container. It may have an adhesive portion provided on at least a part of the surface, and the adhesive portion may be bonded to an opposing outer surface by bending the first and second seal portions.

 The outer surface of the outside of the container is a paper layer according to the configuration of (1), and is a second sealant layer according to the configuration of (2). The same applies to the outer surface of the trunk described in (9).

 In other words, in the liquid paper container of the present invention, the liquid paper container according to the present invention is characterized in that, in the constitution of (5) or (6), at least a predetermined portion of the outer surface of the sealed sealing band is provided with an adhesive member, The surfaces of the side plate, the top plate, the bottom plate, etc. of the container and the outer surface of the seal band, or the outer surfaces of the seal band may be sealed by pressure bonding with an adhesive member.

 (8) In the liquid paper container according to the present invention, in any one of the constitutions (5) to (7), each of the first and second seal portions is made of hot air and a heat seal bar. It may be applied by high frequency or ultrasonic waves.

 In other words, in the liquid paper container of the present invention, in any one of the constitutions (5) to (7), the top seal portion and the bottom seal portion such as the rear plate, the top plate, and the bottom plate have hot air and heat. Sealing may be performed with high frequency or ultrasonic waves.

(9) In the liquid paper container of the present invention, in any one of the constitutions (5) to (8), the first seal portions are bonded to each other by bending the two first ear plates. The two second ear plates are formed so as to be bonded to the outer surface of the body (the second sealant layer or paper layer) by bending. Is also good. Alternatively, the two second ear plates may be formed so that the second seal portions are bonded to each other by bending.

 In other words, in the liquid paper container of the present invention, in any one of the constitutions (5) to (8), the ear plate of the top seal portion is pressure-sealed on the top plate surface or the side plate surface, and the lug of the bottom seal portion is formed. The plate may be pressure-sealed to the bottom plate surface.

 (10) In the liquid paper container according to any one of the constitutions (7) to (9), the liquid paper container according to any one of the constitutions (7) to (9), As the bonding portion, a material having a lower melting point than the sealing material used for hermetic sealing of the first and second sealing portions may be used.

BRIEF DESCRIPTION OF THE FIGURES

 FIGS. 1A and 1B are cross-sectional views showing a configuration example of a paper container laminate sheet according to a first embodiment of the present invention.

 FIG. 2A and FIG. 2B are development views showing a planar configuration of a blank material produced from the laminated sheet.

 3A to 3D are process cross-sectional views for explaining skiving processing performed on the blank material.

 4A to 4D are cross-sectional views showing a configuration example of an adhesive member used for a blank material.

 5A to 5C are perspective views for explaining an assembling process of the bottom plate portion of the liquid paper container.

 6A and 6B are perspective views for explaining an assembling process of the lid plate portion of the liquid paper container.

FIG. 7 shows a laminated sheet for a paper container according to the second embodiment of the present invention. It is sectional drawing which shows the example of a structure of a mouse | mouth.

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

 (First Embodiment)

 1A and 1B are cross-sectional views illustrating a configuration example of a laminated sheet for a paper container according to a first embodiment of the present invention. As shown in FIG. 1A, the laminated sheet (laminated material for paper container) 8 is composed of a paper layer 1 thermoplastic resin 3 (for example, unstretched polypropylene resin (CPP)), a norm layer 5, and a sealant. Layer 6 is stacked in this order.

 More specifically, a multilayer film 7 in which a thermoplastic resin layer 3 and a barrier layer 5, and a barrier layer 5 and a sealant layer (first sealant layer) 6 are respectively adhered via an adhesive 4 is a paper layer. Stacked on one.

 That is, the laminated sheet 8 has a structure in which the surface of the thermoplastic resin layer 3 of the multilayer film 7 is sand-laminated to the paper layer 1 via the polypropylene resin 2.

 Note that the laminated sheet 8 may be modified to the laminated sheet 9 shown in FIG. 1B without the thermoplastic resin layer 3. The laminated sheet 9 has a configuration in which a paper layer 1, a nourish layer 5, and a sealant layer 6 are laminated in this order. The paper layer 1 and the barrier layer 5, and the glue layer 5 and the sealant layer 6 are bonded via an adhesive 4, respectively.

The delamination strength of the laminated sheets 8 and 9 is 0.79 NZ It is preferably 15 mm or more.

 The paper layer 1 is obtained by impregnating or applying a resin to a paper base material. As the paper base material, for example, various types of paper such as the following (la) to (If) can be used.

 (la) Paper made of 100% virgin pulp.

 (lb) 100% recycled paper.

 (lc) Paper in which the above (la) and (lb) are mixed at an arbitrary ratio.

(Id) Any one of the above (la) to (lc), and a mixture of an NBKP material obtained from softwood and an LBKP material obtained from hardwood at an arbitrary ratio.

 (le) Paper made of vegetable fiber material such as kenaf bamboo other than wood pulp in the above (la) to (Id).

 (If) Paper obtained by treating the above papers (la) to (le) with crack coating. Further, paper having a strong peeling strength of the laminating layer and having hot water resistance, such as cup base paper, can be particularly preferably used. Here, the cup base paper is a paper obtained by mixing the NBKP material and the LBKP material of 100% virgin pulp and adding a sizing agent and a paper strength agent.

The paper layer 1 is obtained by impregnating or applying a resin capable of imparting hot water resistance to these paper base materials. The paper layer 1 can be further impregnated with a paper strength enhancer when wet, a waterproofing agent, and a water repellent, if necessary. In addition, these paper base materials may be impregnated with a resin that imparts rigidity and water resistance in a papermaking stage or in a secondary processing stage after papermaking. The term “fiber structure” or “paper base” as used herein includes all fiber structures made of pulp or the like, and is referred to as so-called paper. Is not limited to this type.

 When hot water is to be imparted, the resin to be impregnated or applied may be a thermosetting resin such as a silane resin, a melamine resin, a urethane resin, an isocyanate resin, or an acrylic resin. Resins, polyester resins, thermoplastic resins such as polyethylene resins and polypropylene resins can be selected and used depending on the required hot water temperature. Also, even when high water repellency is required as an additional function, the above resin materials can be mixed or mixed according to the required level of water repellency as long as the required hot water resistance is not impaired. It is possible to use it.

 When imparting dry strength, water resistance and wet strength, polyvinyl alcohol resin, polyacrylamide resin, starch, etc. can be used as the resin to be impregnated.

 As the wet strength agent, urea-formaldehyde resin, melamine-formaldehyde resin, starch, polyamide, modified epichlorohydrin, and various latexes can be used. Examples of the various latexes include natural rubber latex, synthetic rubber latex such as SBR, NBR, and polyvinyl chloride, polyvinyl acetate, acrylic resin, polyvinyl chloride, polyvinylidene chloride, or a mixture thereof. There are copolymer resin latex and the like.

 The paper base material is impregnated (internally or externally added) in the papermaking process or in the secondary processing step after papermaking, so that the paper base material is evenly covered throughout the thickness direction of the paper layer 1. Resin can be retained.

In addition, a liquid paper container is used to impregnate the resin during the papermaking stage. The density and thickness of the impregnated paper, the amount of resin to be internally added, and the like can be arbitrarily determined according to the desired functional level of the paper base material.

 Next, a method of impregnating a paper base material with a resin that imparts rigidity, water resistance, and hot water resistance as a secondary process after or after the papermaking process will be described. Examples of the impregnation method by external addition include a dipping method in which the fibrous structure is immersed in the impregnating agent and an excessive amount of the impregnating agent is temporarily applied, or preferably, a predetermined amount of the impregnating agent is applied or impregnated. Gravure coating method and roll coating method. As an impregnation method by external addition, it is also possible to impregnate the impregnating agent from the front and back of the base fiber structure.

Furthermore, in the gravure impregnation method having two or more units, an impregnating agent for impregnating the inside of the paper base material is first applied from one side or both sides, and the impregnating agent penetrates into the base material. After that, a coating unit can be formed on the surface of the paper substrate in the last unit. The obtained impregnated paper has high wet strength, for example, by impregnating the entire inside of the impregnated paper with a wet paper strength enhancer or the like. In addition, a high water-repellent effect can be imparted by disposing a water-repellent agent or the like on the surface layer of the impregnated paper. That is, as long as the impregnating agent can be supplied to the paper substrate, a desired impregnation method can be used depending on the paper substrate and the impregnating agent. Furthermore, since these impregnation methods are secondary processes, they require a small amount of processing compared to the papermaking process, and can be performed at low cost. From the viewpoint of further improving heat resistance, an isocyanate resin is preferable. The isocyanate resin has the property of improving the wet strength of paper when impregnated into a paper base material. I-society and water in paper Since the urea compound formed by the separation has extremely high heat resistance, water resistance and hot water resistance, the isocyanate resin can significantly reduce the water absorption of the paper base material. Therefore, the paper container using the isocyanate resin-impregnated paper has extremely excellent shape retention and buckling strength not only in the dry state but also in the wet state. In addition, paper containers made of heat-resistant water-treated paper impregnated with an isocyanate-based resin exhibit extremely high shape retention under hot water conditions such as boil sterilization and retort sterilization processes, and possess hot water resistance. are doing.

 Well-known polyisocyanate compounds can be used as the isocyanate resin to be impregnated. Well-known polyisocyanate compounds include, for example, phenylene diisocyanate (PDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), 4, 4, diisocyanate and diphenylmethane (MDI) and other aromatic diisocyanates, xylylene diisocyanate (XDI) and other aromatic aliphatic diisocyanates, hydrogenated TDI, hydrogenated XDI, hydrogenated MDI, hexamethylene diisocyanate (HMDI), Aliphatic or alicyclic diisocyanates (IPDI) and their derivatives and polyadducts, burettes, and trimers, which are polyadducts, burettes, and trimers In addition to trifunctional isocyanates such as isocyanate and resin trisodium (LTI), Various cage Goma, including Ane door, there is a polymer.

When filling a paper container using the paper layer 1 with liquid food, it is preferable to use XDI or IPDI. The amount of impregnation may be set so that the impregnated paper has a tensile strength when wet of 10% or more when dry. According to such a setting, heat resistance and water resistance can be improved, and shape retention and rigidity of the container when wet can be maintained.

 The thermoplastic resin layer 3 is made of a thermoplastic resin having heat resistance and moisture resistance. Examples of such thermoplastic resins include block-type or random-type undrawn polypropylene (CPP), polyamide (nylon), medium-density polyethylene (MDPE), and high-density polyethylene. Films such as (HDPE) can be preferably used. The thickness of this film is not particularly limited, but is preferably about 40 m.

 The barrier layer 5 is provided between the paper layer 1 and the sealant layer 6 and has a function of imparting gas barrier properties and water vapor barrier properties to the laminated sheet. As the barrier layer 5, for example, a metal foil, a metal compound vapor-deposited film, an inorganic compound vapor-deposited film, or a barrier plastic film can be used.

 Here, the metal foil is typically an aluminum foil. The thickness of the aluminum foil is, for example, about 6 to 50 m.

 The metal compound vapor deposited film is generally a metal film made of a plastic film such as polyethylene terephthalate film, nylon film, polypropylene alcohol film, etc., aluminum titanium, zirconium, tin or a composite thereof. A compound formed by applying a thin film of, for example, about 20 to 200 nm by a vacuum evaporation method is preferably used.

The plastic film supporting the above deposited film In addition, for example, a polyester film, a polyamide film, a polyolefin film, a polycarbonate film, a saponified ethylene monovinyl acetate copolymer film, or the like can be used.

 In the description of the metal compound vapor-deposited film, the inorganic compound vapor-deposited film may be made of, in place of the metal compound, silicon oxide, aluminum oxide, magnesium oxide, calcium oxide, or a composite thereof. Those using a compound can be preferably used. The thickness of the inorganic compound is preferably about 20 to 200 nm as described above.

 As the non-uniform plastic film, a film made of polyvinylidene chloride, ethylene-vinyl alcohol, or the like, or a film coated with these resins is preferably used.

 More specifically, different materials are used for the barrier plastic film in terms of barrier properties such as water vapor and water and oxygen gas barrier properties.

 In the case of barrier properties such as steam and water, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, and polypropylene that have barrier properties such as steam and water Films or sheets of resins such as copolymers can be preferably used.

In the case of oxygen gas barrier property, polyester resin, polycarbonate resin, nylon resin (polyamide resin), acrylonitrile resin, polyvinyl resin having oxygen gas barrier property A film or a sheet of a resin such as alcohol, an ethylene-vinyl acetate copolymer, or another resin can be preferably used.

 The barrier-unique plastic film can use one or more combinations of materials. The thickness of the barrier-compatible plastic film is optional, but is usually preferably 6 to 100 mm, and more preferably 7 to 30 m.

 The type to be selected as the barrier layer 5 may be appropriately determined depending on the purpose and use of the laminated sheet. The sealant layer 6 only needs to be a resin layer having heat sealing properties. Polypropylene, polyethylene terephthalate, polyethylene or the like can be preferably used.

 The sealant layer 6 may be made of a film such as a non-stretched polypropylene (CPP), a medium-density polyethylene (MDPE), or a high-density polyethylene (HDPE). Since the amount of the low-molecular-weight substance to be extracted is small, a block type having a small effect on the taste of the contents in boil sterilization or retort sterilization treatment is preferably used.

 The sealant layer 6 may include a vapor deposited layer such as an aluminum vapor-deposited unstretched polypropylene film.

In addition, when the sealant layer 6 is required to have retort resistance as well as heat sealing property, cast polypropylene (CPP) film or linear low-density polyethylene (L-LDPE) having excellent heat resistance is used. Film can be preferably used. The thickness of the sealant layer 6 is preferably about 30 to 100 m, more preferably about 50 im. Is more preferable.

 The adhesive 4 includes a heat-resistant polyurethane resin polyacrylate (methyl methacrylate, ethyl acrylate, butyl acrylate, etc.) and various comonomers (acrylic acid ester, Adhesives for retorts such as copolymer resins with methacrylic acid, pinyl acetate, etc.) can be preferably used.

 The laminated sheet 8 as described above is processed into a blank plate 10 for producing a liquid paper container.

 More specifically, the laminated sheet 8 is punched into a size required for a liquid paper container, and a fold line and a diagonal ascending line are inserted in a bent portion, as shown in FIG. 2A or FIG. 2B. The blank plate 10 shown in Fig. 2A is sequentially processed through the folding line in the central band area along the horizontal direction in Fig. 2A, and the rear plate 11, the side plate 12, and the front plate 1 3. Side plate 14 and rear plate 15 are provided.

 The rear plates 11 and 15 are each provided with a lid plate 16 at the upper end continuously through the bent line, and a bottom plate 17 at the lower end similarly through the bent line. I have. The bottom plate 17 has a skewed S line 18a.

 On the other hand, the side plates 12 and 14 are provided with ear plates 19 at the upper and lower ends continuously via folding lines. The earplate 19 has two oblique lines 18.

 The front plate 13 is provided with a cover plate 20 at the upper end continuously through a folding line, and a bottom plate 21 at the lower end continuously through a go line.

Cover plates 16 and 20, bottom plates 17 and 21 and ear plates 19 A band-shaped glue strip 22 is continuously provided on the outer end of the work board 10 via a folded line.

 Further, the rear plate 15 and the lid plate 16 and the bottom plate 17 on the upper and lower ends thereof are continuously connected to the outer end of the blank plate 10 via the folding line 23, respectively, in the form of a band-shaped glue allowance panel portion 2. 4 are provided.

 Since the glue margin panel 24 is located inside the container when the liquid paper container is manufactured, it is an area where the skiving hemming processing described later is performed, and extends to the glue margin piece 22 described above. It is set up.

 An adhesive member 25 is adhered to a plurality of areas on the glue margin piece 22, the glue margin panel part 24, and the area in the vicinity thereof. The adhesive portion of the adhesive member 25 is determined by folding the triangular ear plate 19 formed by folding to the lid plate 16 side, the bottom plate 17 side, or the side plate 12 or 14 side. It can be set as desired.

 In the case where the side plates 12 and 14 are bent, adhesive members 25b are adhered to predetermined portions of the side plates 12 and 14.

 Further, the adhesive portion of the adhesive member 25 is not limited to the bending direction of the ear plate 19 and can be appropriately set according to the thickness of the blank plate 10 and the like.

 The blank plate 10a shown in FIG. 2B is different from the blank plate 10 described above, and is different from the blank plate 10a when the liquid paper container is manufactured from the viewpoint of eliminating the need for the Skype hemming process described later. All sections are formed so as to be located outside the container.

Specifically, side portions 26a and 26b are continuously provided on the outer end sides of the side plates 12a and 15a via a folding line. Side 2 6 a and 26b are mutually sealed via the sealant layer 6 so that the cross section of the blank plate 10a is outside the container. Therefore, unlike the blank plate 10a shown in FIG. 2A, the blank plate 10a shown in FIG. 2B does not require a skypeening process for reinforcing the cross section.

 Next, skiving processing performed on the blank 10 shown in FIG. 2A will be described with reference to FIGS. 3A to 3D.

 The blank material 10 is punched into a desired blank shape, with the surface of the sealant layer 6 of the multilayer film 7 as the inner surface.

 Thereafter, as shown in FIG. 3A, the blank material 10 is heat-sealed with a heat-resistant hot melt or an adhesive member 25 at the end of the paper layer 1 corresponding to the glue margin panel portion 24.

 As shown in Figure 3B, the end of the paper layer 1 that has been melt-sealed is subjected to Skype processing P1 to prevent the penetration of the contents from the end face and leakage of the liquid. A part 24 is formed.

 As shown in FIG. 3C, the glue allowance panel portion 24 has a half of the skived portion P1 turned back, and the overlapped inner surface is bonded with an adhesive 13b. Thereby, hemming P2 is completed. The adhesive 13 b is different from the adhesive 4 and is made of a heat-resistant hot melt or the like.

 Subsequently, the blank plate 10 is held in a cylindrical shape with the sealant layer 6 inside the container, and as shown in FIG. 3D, the adhesive margin seal portion 24 of each plate 15, 16 17 The adhesive member 25 along the edge faces the other rear plate 11, the lid plate 16, and the end of the bottom plate 17.

After that, hot air treatment and high frequency treatment are applied to the adhesive member 25. Alternatively, ultrasonic treatment is applied, and the rear plates 11, 15 and the lid plate 16 and the bottom plate 17 are sealed. Thereby, the blank plate 10 is processed into a cylindrical shape with the sealant layer 6 inside the container.

 Here, the adhesive member 25 will be described in detail with reference to FIGS. 4A to 4C.

 The adhesive member 25 has a laminated structure in which two sealant layers (27, 29, 30) sandwich the base material layer (28) as shown in each example of FIGS. 4A to 4C. Can be preferably used.

 The adhesive member 25 shown in FIG. 4A is composed of a saturated polyester resin (PET) 27 of about 30 to 60 m that is melt-adhered to the paper layer 1, a polyester resin 28 of about 12 mm, and 30. A saturated polyester resin 27 of about 6 Ozm is laminated with an adhesive 4 interposed therebetween.

 The adhesive member 25 shown in FIG. 4B is made of a non-stretched polypropylene (CPP) 29 of about 20 to 60 m in place of the saturated polyester resin 27 on the upper side in FIG. 4A. This is the configuration used.

The adhesive member 25 shown in FIG. 4C is composed of a non-stretched polypropylene (CPP) 29 of about 20 to 60 m, which melts and adheres to the paper layer 1, and polyester resins 28 and 20 to 60 m This is a configuration in which about 30 single-site catalyst polyethylene 30 is laminated via an adhesive 4. The resins 27, 29, and 30 of the sealant layer are not limited to the examples shown in FIGS. 4A to 4C and can be replaced with each other. The adhesive member 25 has a laminated structure. Not limited to this, a single-layer configuration may be used as shown in FIG. 4D. Adhesive member 25 shown in Figure 4D Is a single-layer structure composed of linear low-density polyethylene (LLDPE) 31 of about 20 to 80 ^ m that is melted and adhered to the paper layer 1. The adhesive member 25 is not limited to this. Instead of LLDPE 31, for example, a non-stretched polypropylene (CPP) 29 of about 20 to 60 m or a heat-resistant hot melt may be used.

 Next, a process of assembling the bottom plates 17 and 21 of the liquid paper container from the skim-hemmed plank plate 10 will be described with reference to FIGS. 5A to 5C.

 The sealant layer 6 of the glue margin 22 on the bottom plate 17, 21 side is treated inside the container by hot air treatment, seal bar treatment, high frequency treatment or ultrasonic treatment as described above. It is assumed that they are sealed together.

 In this state, the liquid food or the like is filled in the bag-shaped liquid paper container, and the sealant layer 6 of each of the adhesive margin pieces 22 on the cover plates 16 and 20 is similarly subjected to hot air treatment or the like. The gasket shall be sealed inside the container.

 Further, the sealed liquid paper container shall have ear plates 19 formed at the four corners by bending the folding line 18. However, the present invention is not limited to this. , 21 Only two earplates 19 may be formed. 6A to 6B are described after the steps of FIGS. 5A to 5C, but the present invention is not limited thereto, and either step may be performed first.

Now, it is assumed that the liquid paper container is in a state in which an ear plate 19 is formed as shown in FIG. 5A. The outside of the container is paper layer 1. The inside of the container is a sealant layer 6.

 Next, when the two ear plates 19 on the bottom plate 17 side are folded upward from the state shown in FIG. 5B, the bottom plate 21 and the ear plates 19 are folded as shown in FIG. 5C. The glue allowance pieces 22 are adhered to each other so as to overlap.

 This completes the process of assembling the bottom plates 17 and 21 of the liquid paper container.

 Next, a process of assembling the lid plates 16 and 20 of the liquid paper container will be described with reference to FIGS. 6A and 6B.

 In the liquid paper container, the ear plates 19 of the cover plates 20 and 19 are folded downward from the state shown in FIG. 6A, and as shown in FIG. 5 is adhered to the paper layer 1 on the surface of the side plates 12 and 14.

 If the ear plate 19 is folded downward and the blank plate 10 is so thick that the ear plate 19 is strongly repelled, etc., the side plate 12, which faces the ear plate 19, An adhesive member 25 b may be provided in advance on 14.

 In any case, the completion of the bonding of the ear plate 19 completes the production of the liquid paper container.

 The liquid paper container after completion of preparation is subjected to retort treatment under the conditions of 121 for 30 minutes, dried, and used for storage and distribution.

As described above, according to the first embodiment, due to the configuration in which the paper layer 1 is impregnated with a resin and subjected to hot water treatment, the strength of the paper base material deteriorates due to the retort sterilization at high temperature and high humidity. Packaging container A liquid paper container which maintains the strength as described above and has excellent drying properties can be produced.

 Since the liquid paper container is mainly composed of paper, it has a low environmental burden, is ecologically compatible, and can be suitably used for heat sterilization of retorts and the like.

 Also, when fabricating a liquid paper container, if the end sections of the laminated sheets 8 and 9 are located inside the container, as shown in Fig. 3A to Fig. 3D, skive hemming is performed. Therefore, the cross section of the end located inside the container can be reinforced.

 In the present embodiment, the case where a brick-shaped paper container is manufactured from the laminated sheets 8 and 9 is described. However, the present invention is not limited to this, and a roof-type container and a tetrahedron are formed from the laminated sheets 8 and 9. The same function and effect can be obtained even if a paper container having an arbitrary shape such as a container or a cup type container is manufactured. This is the same in the following embodiments.

 (Second embodiment)

 FIG. 7 is a cross-sectional view showing a configuration example of a laminated sheet for a paper container according to a second embodiment of the present invention. The same parts as those in FIG. Here, however, the different parts are mainly described.

 That is, the present embodiment is a modification of the first embodiment, and aims at improving the heat sealing property and the antifouling property.

Specifically, the laminated sheet 8 X is different from the laminated sheet 8 described above in that the second sealing layer 30 having a plurality of through holes 3 Oh is formed opposite to the multilayer film 7. It is laminated on the paper layer 1 of the surface. In FIG. 7, the adhesive 2 between the layers 1 and 3 and the The illustration of the adhesive 4 between the layers 3 and 5 and between the layers 5 and 6 is omitted.

 Here, as the second sealant layer 30, for example, polyolefin can be suitably used as a material having excellent heat sealing properties and antifouling properties.

 Examples of the polyolefin include various polyethylene (PE) resins such as low-density polyethylene (LDPE), linear (linear) low-density polyethylene (LLDPE), and others. A film or sheet such as propylene (PP) resin can be used. The thickness of the film or sheet is not particularly limited, but is preferably about 30 m.

 The through hole 30 h is a hole having a uniform diameter of 2πιιηφ or less penetrating the second sealant layer 30, and is provided with at least one or more per 1 cm of the second sealant layer 30.

 As a result, the liquid paper container has an antifouling property to the paper layer 1 by the resin of the second sealant layer 30 and a paper layer 1 by the through hole 30 h of the second sealant layer 30. Air permeability can be obtained at the same time. In addition, even if the paper layer 1 absorbs or absorbs moisture in a processing step such as retort sterilization, the air permeability to the paper layer 1 can be obtained through the through hole 3 Oh of the second sealant layer 30 outside the container. Acts to easily evaporate and remove water in layer 1.

A printing layer can be provided on the surface of the paper layer 1 on the second sealant layer 30 side. As the print layer, a desired ink composition and a desired printing method can be used to form, for example, an arbitrary printed pattern such as a character, a figure, a symbol, a picture, and the like. As the ink composition, for example, a normal gravure ink composition, an offset ink composition, a screen ink composition, or the like can be used. As the printing method, for example, a gravure printing method, an offset printing method, a screen printing method, or a transfer printing method can be used.

 The laminated sheet 8x as described above can be easily manufactured as follows.

 That is, after forming the second sealant layer 30 on the surface of the paper layer 1 on the print layer side by extrusion lamination or the like, a through hole 30 h is formed in the second sealant layer 30. .

 The method for forming the through-holes 3 Oh is not particularly limited, and includes a method of physically forming a needle hole, a method of forming by laser processing, and a method of evaporating and foaming water in the paper layer 1 by heating. An example of a method of forming the same can be given.

 Subsequently, between the paper layer 1 and the thermoplastic resin layer 3, the thermoplastic resin layer 3 and the barrier layer 5, and the barrier layer 5 and the sealant layer 6, on which the second sealant layer 30 is laminated. Dry lamination is performed using the adhesive 4 described above.

 Thereby, a laminated sheet 8x can be manufactured.

As a specific configuration of the laminated sheet 8 x, the second sealant layer 30 [perforated LLDPE layer (30 zm)] Z printing layer Z paper layer 1 (heat-resistant water paper (180 g / m 2)) Z thermoplastic resin layer 3 [Polyamide layer (30 m)] Z barrier layer 5 [Aluminum foil (9 m)] Z sealant layer 6 [CPP layer (50 m)] The laminated structure of the above can be cited as an example. Of course, the laminated sheet 8x is not limited to this example, and the material of each layer 30 and 1 to 6 and the thickness thereof can be arbitrarily changed.

 Further, the present invention is not limited to the laminated structure of the laminated sheet 8X, but may be applied to a laminated structure in which the second laminated layer 30 having the through-hole 3Oh is formed on the surface of the paper layer 1 of the laminated sheet 9 described above. Is also good.

 The laminated sheet 8X as described above is used so that the second sealant layer 30 is located outside the container when a liquid paper container is manufactured. The specific manufacturing method of the liquid paper container is the same as that of the first embodiment according to FIGS. 2A to 2B, 3A to 3D, 5A to 5B, and 6A to 6B. It is.

 The prepared liquid paper container can be used in a process such as boil sterilization or retort sterilization, etc., even if the paper layer 1 absorbs water or moisture. The water in paper layer 1 can be easily evaporated from h.

 Therefore, according to the second embodiment, in addition to the effect of the first embodiment, the through hole 30 h is formed by the configuration in which the second sealant layer 30 having the through hole 30 h is provided. While the moisture is evaporated from the paper layer 1, the portion other than the through-holes 3Oh can protect the surface of the paper layer 1.

 Further, since the second sealant layer 30 protects the surface of the paper layer 1, it is possible to provide a liquid paper container and a laminated sheet excellent in heat sealability, stain resistance and aesthetics.

In addition, since container processing with a heat seal is possible, and it is excellent in suitability for filling molding machine and high-speed processing, the first embodiment It can be processed inexpensively as well.

 (Third embodiment)

 Next, a third embodiment of the present invention will be described.

 This embodiment is a modification of the first or second embodiment, and does not require heat resistance with respect to the adhesive member 25 of the ear plate 19 of the liquid paper container.

 Specifically, after the retort treatment, the steps shown in FIGS. 5A to 5C and the steps shown in FIGS. 6A to 6B, or both steps are executed, so that each step is used. The heat resistance of the adhesive member 25 is not required.

 For example, when the steps shown in FIGS. 5A to 5C and FIGS. 6A to 6B are performed after the retort treatment, a material having no heat resistance to the retort treatment is used as the adhesive member 25. use.

 Also, for example, when the steps of FIGS. 5A to 5C, the retort treatment, and the steps of FIGS. 6A to 6B are sequentially performed, the adhesive member 25 used in the steps of FIGS. Use a material without heat resistance.

 Conversely, when the steps shown in FIGS. 6A to 6B, the retort treatment, and the steps shown in FIGS. 5A to 5C are sequentially performed, the adhesive member 25 used in the steps shown in FIGS. Use a material without heat resistance.

 Here, the material having no heat resistance is a material having a melting point lower than the temperature of the retort treatment, and is generally a material that can be obtained at a low cost, for example, LDPE (low-density polyethylene) or hot-dip. A melt or sealant can be used as appropriate.

Therefore, according to the third embodiment, in addition to the effects of the first or second embodiment applied, the bending step is performed after the retort processing. By executing the method and using a material having no heat resistance as the adhesive member 25, a liquid paper container can be manufactured at a lower cost.

Industrial applicability

 As described above, the laminated material for a paper container and the liquid paper container according to the present invention are useful for forming a retortable paper container while maintaining the strength of the container. Suitable for use in prick-shaped paper containers with folded portions that overlap with crabs.

Claims

The scope of the claims  1. A laminated material for paper containers in which a thermoplastic resin layer (2), a barrier layer (4), and a first sealant layer (6) are sequentially laminated on one side of a paper layer (1),  The paper layer is  A base paper made by impregnating or coating a fiber structure made of paper and pulp-based fiber composite material with any one of the following: an isocyanate resin, a polypropylene resin, a polyethylene resin, or a polyester resin A laminated material for paper containers, characterized by being formed using the same.  2. The paper container laminate material according to claim 1, further comprising a second sealant layer (30) having a plurality of through holes (30h) formed on the other surface of the paper layer (1). A laminated material for paper containers characterized by the following.  3. The laminated material for paper containers according to claim 2, wherein the second sealant layer (30) has a diameter of the through hole (30h) of 2 mm ci) or less, and is formed with the through hole. A laminated material for paper containers, wherein the density is at least one piece per 1 cm 2.  4. A liquid paper container manufactured using the paper container laminated material according to claim 2 or 3,  A liquid paper container, wherein the second sealant layer (30) is arranged outside the container.  5. The liquid paper container according to claim 4, Of the first side to the fourth side of the western square (10, 10a) formed from the paper container laminated material (8x), predetermined first opposing sides are opposed to each other. A square cylindrical body formed by bonding the sides (11, 16, 17 12a, 16, 17) and the ends of the second side (15-17, 15a, 16, 17) to each other. (11-15, lla-15a)  A strip-shaped first layer formed by hermetically sealing the first sealant layers (6) at the ends of the third sides (17, 19, 21, 17, 19, 19a). 1 Seal part (22)  A strip-shaped first layer formed by hermetically sealing the first sealant layers (6) at the ends of the fourth sides (16, 19, 20, 16, 19, 20a) with each other. 2 Seal part (22)  Two substantially triangular first ear plates (19) bent at both ends of the first seal portion;  Two substantially triangular second ear plates (19) bent at both ends of the second seal portion;  A liquid paper container comprising:  6. The liquid paper container according to claim 5,  When one end (15-17) of the ends of the first side and the second side is located inside the container, the end inside the container is formed on the paper layer (1). A liquid paper container characterized by having a Skype processing part (P2).  7. The liquid paper container according to claim 6, wherein  The first seal portion (22) has an adhesive portion (25) provided on at least a part of the second sealant layer (30) outside the container, The liquid paper container, wherein the bonding portion secures the two first ear plates (19) by bending the two first ear plates (19). 8. The liquid paper container according to claim 7, wherein each of the first and second seal portions (22) is provided with a hermetic seal using hot air, a heat seal bar, high frequency or ultrasonic waves. A liquid paper container characterized by the above-mentioned.  9. The liquid paper container according to claim 8, wherein  The bonding portion (25) outside the container of the first seal portion (22) and the bonding portion (25) outside the container of Z or the second sealing portion (22) are formed of the first and second sealing portions. A liquid paper container made of a material having a lower melting point than a sealing material used for a hermetic seal.  10. The liquid paper container according to claim 5,  The first and second ear plates (22) are connected to each other through an adhesive portion (25) provided on at least a part of the second sealant layer (30) outside the container. A liquid paper container, wherein the first and second ear plates (19) are fixed by bending in (19).  11. The liquid paper container according to claim 10, wherein the first and second seal portions (22) are each hermetically sealed by hot air, a heat seal bar, high frequency or ultrasonic waves. Liquid paper container characterized by the following.  12. The liquid paper container according to claim 11, wherein the first sealing portion (22) has a bonding portion (25) outside the container and the Z or the second sealing portion (22) has a bonding portion outside the container. The liquid paper container, wherein the part (25) is made of a material having a lower melting point than a sealing material used for hermetically sealing the first and second seal parts. 13. A liquid paper container manufactured using the paper container laminate material according to claim 1. Among the first to fourth sides of the square (10, 10a) formed from the paper container laminated material (8), predetermined first sides (11, 16, 17, 12a, 16) opposed to each other. , 17) and the end of the second side (15-17, 15a, 16, 17) are bonded to each other, and the first sealant layer (6) is disposed inside the container. And the cylindrical body (11-15, 11a-15a)  A strip-shaped first seal formed by hermetically sealing the first sealant layers (6) at the ends of the third sides (17, 19, 21, 17, 19, 19a). Part (22),  A band-shaped second seal formed by sealingly sealing the first sealant layers (6) at the ends of the fourth sides (16, 19, 20, 16, 19, 20a). Part (22),  Two substantially triangular first ear plates (19) bent at both ends of the first seal portion;  Two substantially triangular second ear plates (19) bent at both ends of the second seal portion;  A liquid paper container comprising:  14. The liquid paper container according to claim 13, wherein  Either one of the ends of the first side and the second side When (15-17) is located inside the container, the end portion inside the container is provided with a skiving portion (P2) formed on the paper layer (1). container.  15. The liquid paper container according to claim 14, wherein The first seal portion (22) has an adhesive portion (25) provided on at least a part of the paper layer (1) outside the container, The adhesive portion is formed by bending the two first ear plates (19). The liquid paper container, wherein the two first ear plates (19) are fixed.  16. The liquid paper container according to any one of claims 13 to 15, wherein:  The liquid paper container, wherein the first and second seal portions (22) are each sealed with hot air, a heat sealer, or high frequency or ultrasonic waves.  17. The liquid paper container according to claim 16, wherein  The adhesive part (25) outside the container of the first seal part (22) and / or the adhesive part (25) outside the container of the second seal part (22) is formed of the first and second seal parts. A liquid paper container, wherein the sealing material used for the hermetic seal is also made of a material having a low melting point.  18. The liquid paper container according to claim 13, wherein  The first and second seal portions (22) are connected to the first and second ear plates (19) via an adhesive portion (25) provided on at least a part of a paper layer (1) outside the container. A liquid paper container characterized in that the first and second ear plates (19) are fixed by bending the first and second ear plates (19).  19. The liquid paper container according to claim 13 or claim 18, wherein:  The liquid paper container, wherein the first and second seal portions (22) are each sealed by hot air, a heat seal bar, or high frequency or ultrasonic waves.  20. The liquid paper container according to claim 19, An adhesive portion (25) of the first seal portion (22) outside the container, and / or Is characterized in that the bonding part (25) on the outside of the container of the second seal part (22) is made of a material having a lower melting point than the sealing material used for the hermetic seal of the first and second seal parts. Liquid paper container.