Packaging

Abstract

To provide a packaging material with excellent heat-sealing properties. [Solution] A packaging body in which a first seal layer containing PHBH and a second seal layer are heat-sealed, and the second seal layer is a polyester-based unstretched resin layer, and A packaging body comprising a first seal layer containing PHBH and a second seal layer that are heat-sealed, wherein the second seal layer is a polyethylene-based unstretched resin layer and the first seal layer contains EVA.

Description

[Technical Field]

[0001] This invention relates to packaging. [Background technology]

[0002] In recent years, the development of environmentally friendly packaging using biodegradable materials has attracted attention, and its application to paper containers such as paper cups and plates, and paper containers such as blister packs with uneven surfaces, is expected. Aliphatic polyesters such as polylactic acid and polycaprolactone are known as biodegradable materials, but aliphatic polyesters have the problem that they take a long time to biodegrade at low temperatures and decompose slowly in natural environments such as the ocean. Poly(3-hydroxybutyrate) resins are microbially produced thermoplastics with excellent biodegradability under both aerobic and anaerobic conditions, and possess the remarkable property of being rapidly decomposed by microorganisms even in water such as oceans. Furthermore, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter also referred to as PHBH), a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate, is attracting attention due to its biodegradability and resin properties.

[0003] Patent Document 1 describes a paper substrate coated with PHBH and adhesive on one side, with a basis weight of 150 g / m². 2 More than 600g / m 2 The following coated paper has been proposed that possesses heat-sealing properties and can be used for packaging. Here, it was found that in packaging having a container body and a lid, if PHBH is used for one part and a commonly used thermoplastic resin such as polyethylene or polypropylene is used for the other part and heat-sealed, the heat seal strength may be insufficient. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-195716 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of this invention is to provide a packaging material with excellent heat-sealing properties. [Means for solving the problem]

[0006] The means for solving the problems of the present invention are as follows. 1. The first seal layer and the second seal layer, which contain PHBH, are heat-sealed. A packaging body characterized in that the second sealing layer is a polyester-based unstretched resin layer. 2. The packaging according to 1, characterized in that the first sealing layer contains EVA. 3. The first seal layer containing PHBH and the second seal layer are heat-sealed. The second sealing layer is a polyethylene-based unstretched resin layer. A packaging body characterized in that the first sealing layer includes EVA. 4. The packaging according to 2. or 3., characterized in that the glass transition temperature of the EVA is -50°C or higher and 30°C or lower. 5. The packaging according to any one of claims 1 to 4, characterized in that the first sealing layer and the second sealing layer are provided on different members. 6. The packaging according to any one of claims 1 to 4, characterized in that the first sealing layer and the second sealing layer are provided in different regions of the same member. 7. The packaging according to any one of claims 1 to 6, characterized in that either or both of the first seal layer and the second seal layer are coated layers. 8. The packaging according to any one of claims 1 to 6, characterized in that either or both of the first seal layer and the second seal layer are laminate layers. 9. The packaging according to any one of claims 1 to 6, characterized in that either or both of the first seal layer and the second seal layer are film layers. 10. The package according to any one of 1 to 9, wherein either or both of the first seal layer and the second seal layer are formed on a paper substrate.

Effect of the Invention

[0007] The first package of the present invention, in which the second seal layer is a non-stretched resin layer of polyester-based, has excellent heat sealability and can be firmly joined. The first package of the present invention, in which the first seal layer containing PHBH further contains EVA, is even more excellent in heat sealability. The second package of the present invention, in which the second seal layer is a non-stretched resin layer of polyethylene-based and the first seal layer containing PHBH further contains EVA, has excellent heat sealability and can be firmly joined.

Mode for Carrying Out the Invention

[0008] In the first package of the present invention, the first seal layer containing PHBH and the second seal layer are heat-sealed, and the second seal layer is a non-stretched resin layer of polyester-based. In the second package of the present invention, the first seal layer containing PHBH and the second seal layer are heat-sealed, the second seal layer is a non-stretched resin layer of polyethylene-based, and the first seal layer contains EVA. Here, in this specification, the description of "A to B" (A and B are numerical values or ratios) means a numerical range including A and B.

[0009] (Base material) In the first and second packages, the base materials on which the first seal layer and the second seal layer are formed can be used without particular limitation as long as they are for package applications. Examples of the base materials include paper, resin, etc. Paper or biodegradable resin is preferred, and paper is more preferred. When the first seal layer and the second seal layer are provided as separate members, the base materials on which the first seal layer is provided and the base materials on which the second seal layer is provided may be of the same type or different types. Also, when using a resin base material, the resin base material itself such as a film may constitute the first or second seal layer. Note that a biodegradable resin is a resin that is decomposed by microorganisms into at least water and carbon dioxide, and means a resin with an aerobic biodegradation rate of 50% or more in 6 months measured by a method conforming to ISO-14855-2 (2018).

[0010] (Resin base material) As the resin base material, known ones used in packages can be used without particular limitation. Examples include polyethylene, polypropylene, polyester, nylon, cellophane, etc., and laminates of these can also be used. Also, the resin base material may have a vapor deposition layer of metal or metal oxide formed thereon.

[0011] (Paper base material) The paper base material is a sheet mainly made of pulp and is obtained by papermaking a paper stock containing fillers, various auxiliaries, etc. The paper base material can have a coating layer such as a water vapor barrier layer, a gas barrier layer, an anchor layer, a pigment coating layer, etc. on at least one surface as needed. The basis weight of the paper base material can be appropriately selected according to various desired qualities and its uses, etc., but usually it is preferably 20 g / m 2 or more and 600 g / m 2 or less, more preferably 25 g / m 2 or more and 600 g / m 2 or less. For example, when making a cardboard box, a paper tube, the body of a paper tray, the body member or bottom member of a paper cup, etc., the basis weight of the paper base material is preferably 100 g / m 2 or more and 600 g / m 2 or less, more preferably 120 g / m 2 or more, and even more preferably 150 g / m 2The above is even more preferable, and also 500g / m 2 The following is more preferable: 400g / m 2 The following is even more preferable: 300 g / m 2 The following is even more preferable. Furthermore, when used as flexible packaging material, lid material for paper trays or paper cups, the basis weight of the paper base material should be 20 g / m². 2 More than 100g / m 2 The following is preferable: 25 g / m 2 The above is more preferable, and also 80g / m 2 The following are preferable. Note that flexible packaging materials are packaging materials that are highly flexible among packaging materials.

[0012] The density of the paper substrate can be selected as appropriate depending on the desired quality and handling requirements, but it is typically 0.5 g / cm³. 3 More than 1.0g / cm 3 The following are preferred. In the present invention, the paper substrate may be either paper consisting of only a single paper layer or multilayer paper having two or more paper layers. If the paper substrate is multilayer paper, the pulp, basis weight, etc. of each paper layer may be the same or different.

[0013] (First sealing layer) The first sealing layer contains PHBH. <phbh> PHBH is a copolymer of 3-hydroxybutyrate (hereinafter also referred to as 3HB) and 3-hydroxyhexanoate (hereinafter also referred to as 3HH), and is a biodegradable resin known to be produced by microorganisms. In the present invention, PHBH may be derived from microorganisms or from petroleum resources, but it is preferable to use PHBH derived from microorganisms from the viewpoint of reducing environmental impact.

[0014] The composition ratio (mol%) of PHBH is preferably 3HB:3HH = 97:3 to 75:25, and more preferably 95:5 to 85:15. If the 3HH composition is less than 3 mol%, the properties of PHBH become similar to those of the 3HB homopolymer, resulting in a loss of flexibility and an undesirable tendency for the film deposition temperature to become too high. If the 3HH composition exceeds 25 mol%, the crystallization rate becomes too slow, making it unsuitable for film deposition, and the degree of crystallinity decreases, which tends to make the resin more flexible and reduce its flexural modulus. The composition ratio of PHBH can be measured by NMR analysis of the powder obtained by centrifuging an aqueous dispersion and drying it. Microbially produced PHBH is a random copolymer. Methods to adjust the molar ratio of the copolymer include selecting the microbial cells, selecting the carbon source as the raw material, blending with PHBH of different molar ratios, and blending with 3HB homopolymer.

[0015] The weight-average molecular weight of PHBH is preferably between 50,000 and 1,500,000. When PHBH is within this range, film formation is possible at low temperatures when coating with PHBH, and when PHBH is laminated, a film with excellent mechanical properties can be obtained. A weight-average molecular weight of 100,000 to 500,000 is more preferable, and 150,000 to 450,000 is even more preferable. The weight-average molecular weight of PHBH can be determined by gel permeation chromatography (GPC, such as Showa Denko's "Shodex GPC-101") using a polystyrene gel column (such as Showa Denko's "Shodex K-804") with chloroform as the mobile phase, and the molecular weight converted to polystyrene equivalent. For measurement, a powder obtained by centrifuging and drying an aqueous dispersion containing PHBH is used.

[0016] <eva> In the first packaging, the first seal layer preferably contains EVA (ethylene vinyl acetate copolymer) from the viewpoint of heat sealability. The second packaging has a first sealing layer that includes EVA. The first seal layer containing EVA preferably contains 10 to 250 parts by mass of EVA per 100 parts by mass of PHBH, more preferably 13 parts by mass or more, even more preferably 16 parts by mass or more, even more preferably 19 parts by mass or more, and even more preferably 246 parts by mass or less, even more preferably 242 parts by mass or less, and even more preferably 238 parts by mass or less.

[0017] In EVA, the molar ratio of ethylene to vinyl acetate (component units derived from ethylene:component units derived from vinyl acetate, also expressed as ethylene:vinyl acetate, with a total of 100) is preferably 1:99 to 60:40 from the viewpoint of heat seal strength. This molar ratio is more preferably 3:97 to 50:50, even more preferably 5:95 to 40:60, and even more preferably 7:93 to 30:70. In addition to ethylene and vinyl acetate, EVA can also contain other monomers as monomers. When EVA contains other monomers as monomers, the content of constituent units derived from other monomers relative to the total EVA is preferably 30% by mass or less. This content is not particularly limited as long as it does not impair the effects of the present invention, but for example, it can be 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, etc.

[0018] The glass transition temperature of EVA is preferably -50 to 30°C from the viewpoint of heat seal strength. More preferably -40°C or higher, even more preferably -30°C or higher, even more preferably -20°C or higher, even more preferably -10°C or higher, even more preferably 20°C or lower, and even more preferably 15°C or lower. In this specification, the glass transition temperature refers to the intermediate glass transition temperature measured in accordance with JIS K 7121-1987.

[0019] (Second sealing layer) In the first packaging, the second seal layer is a polyester-based unstretched resin layer. Examples of polyester-based resins included in the second seal layer include polyethylene terephthalate (PET), polybutylene terephthalate, polycaprolactone, polybutylene succinate adipate, polybutylene succinate (PBS), polylactic acid, polybutylene adipate terephthalate, and polybutylene azelate terephthalate. Two or more uniformly compatible resins can also be mixed and used. Among these, PET and PBS are preferred. However, the ratio of PHBH to the total thermoplastic resin included in the second seal layer is 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and most preferably 0 parts by mass.

[0020] In the second packaging, the second seal layer is a polyethylene-based unstretched resin layer. The polyethylene-based resin is a polymer of 50 mol% to 100 mol% of monomers and 0 mol% to less than 50 mol% of any α-olefin. Examples of polyethylene-based resins include LDPE, LLDPE, HDPE, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer, with LDPE and LLDPE being preferred.

[0021] Hereafter, the first seal layer and the second seal layer will be collectively referred to as the seal layer. The sealing layer may be a coated layer, a laminated layer, or even the surface of a resin substrate such as a film layer. Furthermore, the first and second sealing layers are not limited to being formed by the same method; for example, one may be a coated layer and the other a laminated layer or a film layer.

[0022] If the sealing layer is a coating layer, it may contain other thermoplastic resins and inorganic pigments. Additionally, it may contain, as needed, various additives used in coating solutions in the papermaking field, such as dispersants, viscosity modifiers, water-retaining agents, defoamers, water-resistant agents, pH adjusters, cationic resins, anionic resins, UV absorbers, metal salts, lubricants, coloring dyes, and pigments. Other thermoplastic resins that have heat-seal properties at the temperature at which the first seal layer and the second seal layer are fused can be used without particular limitation, but biodegradable resins such as aliphatic polyester resins such as polycaprolactone, polybutylene succinate adipate, polybutylene succinate, and polylactic acid, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate and polybutylene azelate terephthalate are preferred.

[0023] If the first seal layer contains other thermoplastic resins, the total ratio of PHBH and EVA to the total thermoplastic resin contained in the first seal layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and most preferably 100% by mass.

[0024] If the second seal layer contains other thermoplastic resins, the ratio of polyester resin or polyethylene resin to the total thermoplastic resin contained in the second seal layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and most preferably 100% by mass.

[0025] As inorganic pigments, those used in coating paper can be used without particular limitations. Examples include kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, bentonite, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white. One or more of these can be used. Among these, one or more of kaolin, heavy calcium carbonate, light calcium carbonate, mica, talc, and bentonite are preferred.

[0026] From the viewpoint of adhesion to the coating layer, it is preferable that the inorganic pigment has a 50% volume average particle diameter (D50, hereinafter also referred to as "average particle diameter") of 6.0 μm or less, as measured by laser diffraction / scattering. Examples of laser diffraction / scattering measurement devices include Horiba's particle size distribution analyzer "Partica" and Malvern's particle size distribution analyzer "MASTER SIZER S". From the viewpoint of adhesion to the coating layer, the average particle diameter of the inorganic pigment is more preferably 5.0 μm or less, even more preferably 4.0 μm or less, even more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. There is no particular lower limit to the average particle diameter of the inorganic pigment, but from the viewpoint of dispersibility, for example, it is preferably 0.1 μm or more, and more preferably 0.2 μm or more. When two or more inorganic pigments are included, it is preferable that the average particle size of at least one of them is within the numerical range described above, and it is preferable that the proportion of inorganic pigments satisfying this average particle size to the total inorganic pigments is 50% by mass or more, and more preferably 70% by mass or more.

[0027] When the sealing layer, which is a coating layer, contains an inorganic pigment, the solid content mass ratio of the total thermoplastic resin to the inorganic pigment (thermoplastic resin:inorganic pigment, total of 100) is preferably 90:10 to 0.01:99.99. By further blending an inorganic pigment into a coating liquid containing a thermoplastic resin, the adhesion and heat sealability of the resulting sealing layer are improved. Although the mechanism is unknown, the inventors speculate that because inorganic pigments have better thermal conductivity than thermoplastic resins, which are organic materials, the inorganic pigment heats up quickly when heated, and this heat is transferred from the inorganic pigment to the thermoplastic resin, causing the thermoplastic resin to heat up sufficiently and become easily melted and softened. The solid content mass ratio of thermoplastic resin to inorganic pigment (thermoplastic resin:inorganic pigment, total 100) is more preferably 70:30 to 1:99, even more preferably 60:40 to 2:98, and even more preferably 50:50 to 3:97, from the viewpoint of adhesion of the coating layer.

[0028] If the sealing layer is a coated layer, the coating amount is 3 g / m² per side by dry mass. 2 More than 20g / m 2 The following is preferable. This coating amount is 3 g / m 2 Below this amount, heat sealability may decrease. Also, this coating amount is 20 g / m². 2 Beyond this point, the heat sealability does not improve significantly, and material costs, drying costs, and time increase. The sealing layer, which is the coating layer, may be a single layer or a multilayer structure of two or more layers. By constructing the sealing layer as a multilayer structure of two or more layers, defects such as uneven coating can be reduced compared to the case of a single layer. When the sealing layer is constructed as a multilayer structure of two or more layers, it is preferable that the total dry mass of the sealing layers laminated on one side be within the above range, and the coating amount per layer be 2 g / m² in dry mass. 2 It is preferable that the above conditions are met.

[0029] When the sealing layer is a coated layer, the coating method is not particularly limited and can be applied using known coating equipment and coating systems. For example, coating equipment can include blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, roll coaters, reverse roll coaters, size press coaters, gate roll coaters, and the like. The coating system may be either a water-based coating using a solvent such as water, or a solvent-based coating using a solvent such as an organic solvent, but a water-based coating is preferred from a safety and health standpoint. When a water-based coating is used, a water-dispersible resin or a water-soluble resin is used as the thermoplastic resin, so the sealing layer is preferably a coating layer of a water-dispersible resin or a water-soluble resin.

[0030] If the seal layer is a laminate layer, it may contain inorganic pigments. Additionally, it may contain various additives used in papermaking for laminate layers, such as pigments, dyes, lubricants, release agents, plasticizers, UV absorbers, antioxidants, weathering modifiers, and crystal nucleating agents, as needed. When the sealing layer is a laminate layer, the thickness of the sealing layer is preferably between 20 μm and 100 μm. If the thickness is less than 20 μm, heat sealing performance may not be ensured. Also, if the thickness exceeds 100 μm, it is undesirable from a cost perspective. When the sealing layer is a laminate layer, the method of forming it is not particularly limited, and various methods such as extrusion lamination, wet lamination, and dry lamination can be used as appropriate for lamination.

[0031] (packaging) The packaging according to the present invention has a first seal layer containing PHBH and a second seal layer that are heat-sealed. When the first sealing layer and the second sealing layer are provided on different components, the packaging can be a combination of a tray and a lid, or a cup body and a lid, etc. When the first seal layer and the second seal layer are provided in different areas of the same member, they can be provided on different surfaces of a sheet-like member, or in different areas of the same surface. Examples of packaging include cylindrical members, body members, pillow bags, sealed bags, etc., which constitute at least a part of the packaging.

[0032] The packaging of the present invention conforms to JIS Z1707:2019 7.4 "Heat seal strength test". The first and second seal layers were measured according to the following standards, at a pressurized temperature of 130°C and a pressurized pressure of 0.29 MPa (29.4 N / cm²). 2 ) When a heat-sealed product that has been heat-sealed for a pressurizing time of 3.0 seconds is peeled off in a T-shape, the heat seal strength is preferably 2.0 N / 15 mm or more, more preferably 2.5 N / 15 mm or more, even more preferably 3.0 N / 15 mm or more, even more preferably 3.5 N / 15 mm or more, and even more preferably 4.0 N / 15 mm or more. Furthermore, the heat seal strength of the packaging body of the present invention, measured in the same manner except that the pressurizing temperature is 150°C, is preferably 2.5 N / 15 mm or more, more preferably 3.0 N / 15 mm or more, even more preferably 3.5 N / 15 mm or more, and even more preferably 4.0 N / 15 mm or more. [Examples]

[0033] The present invention will be specifically described below with reference to examples, but the present invention is of course not limited to these examples. Unless otherwise specified, parts and % in the examples refer to parts by mass and mass%, respectively. • Heat seal strength The test was conducted in accordance with JIS Z1707:2019 7.4 "Heat seal strength test". A 100mm square test specimen was cut out, and the first and second seal layers were brought into contact. The test was then conducted at pressurized temperatures of 130°C, 150°C, or 180°C, with a pressurized pressure of 0.29 MPa (29.4 N / cm²). 2 After heat sealing with a pressurization time of 3.0 seconds, in an environment of 23℃ and 50% humidity The sample was left to stand for 24 hours, and then a measurement sample was cut from the heat-sealed 100mm square test piece so that the long side was 100mm and the short side was 15mm. Subsequently, the peeled long edge ends were clamped in the upper and lower fixtures of a vertical tensile testing machine (Tensilon, manufactured by A&D Company, Ltd.), and the sample was peeled from the long edge side at a speed of 200 mm / min (T-type), while measuring the peel strength, i.e., the HS strength (N / 15 mm). The measurement was performed twice, and the average value of the peel strength is shown. Furthermore, the heat sealability was evaluated according to the following criteria. Regarding the state of material breakage, if the second seal layer is a film, the first seal layer, which is made of paper, was evaluated by checking for the presence or absence of paper peeling (material breakage). If the second seal layer is paper (laminated paper or coated paper), both the first and second seal layers are made of paper, but in this case, material breakage was evaluated by checking for the presence or absence of paper peeling (material breakage) in either the first or second seal layer. For example, if the paper of the first seal layer broke, it was considered material breakage, and if the paper of the second seal layer broke, it was also considered material breakage, and the degree of breakage was judged as "◎" or "〇", respectively. If there was no paper peeling (material breakage), but delamination occurred between the first and second seal layers, it was judged as "△". If there was no adhesive strength between the first and second seal layers, it was judged as "×". (Adhesion status) ○: Bond across the entire surface of the heat-sealed area. △: Partially adhered with a heat-sealed surface. ×: Not heat-sealed. (Material in a broken state) ◎: Paper peeling (material tearing) across the entire heat-sealed surface. ○: Partial peeling of the paper (material tearing) on ​​the heat-sealed surface. △: Delamination occurs between the first and second seal layers (without material breakage). ×: Not heat-sealed.

[0034] (material) Paper base material: basis weight 220g / m 2 Cup base paper (manufactured by Nippon Paper Industries, CUP-HD220g / m²) 2 ) PHBH: Manufactured by Kaneka Corporation, mass-average molecular weight 600,000 EVA1: Sumika Chemtex Co., Ltd., Sumikaflex S-355HQ, Tg 10℃, Ethylene:Vinyl Acetate = 10:90, Tensile Strength 20.6 MPa, Elongation 420% EVA2: Sumika Chemtex Co., Ltd., Sumikaflex S-400HQ, Tg 0℃, Ethylene:Vinyl Acetate = 20:80, Tensile Strength 12.7 MPa, Elongation 550%

[0035] (Coated paper having a first sealing layer) PHBH and EVA were mixed and stirred in the parts by mass shown in Tables 1-3 to obtain a coating solution with a solid content concentration of 40% by mass. Apply an undercoat liquid at a dry weight of 3 g / m² to one surface of the paper substrate. 2 Bar blade The coating was applied according to the method and dried at 105°C for 1 minute. Furthermore, a top coating liquid was applied to the undercoat at a dry mass of 3 g / m². 2 The paper was coated using the barblade method, dried at 105°C for 1 minute, and then dried further at 160°C for 3 minutes to obtain coated paper having a first seal layer.

[0036] (Second sealing layer) The following was used as the second sealing layer. In Tables 1-3, the "〇" notation for the second sealing layer indicates the one that was used. • LDPE: Base paper (manufactured by Nippon Paper Industries, silver, basis weight 50g / m²) 2 A laminated paper in which unoriented LDPE (Tosoh Corporation, Petrocene 203, 25 μm thick) is laminated to the matte side of the front and back surfaces (glossy or matte) of the paper using a dry lamination method. • LLDPE: Base paper (manufactured by Nippon Paper Industries, silver, basis weight 50g / m²) 2 A laminated paper in which unstretched LLDPE (manufactured by Futamura Chemical Co., Ltd., LL-XMTN, 30 μm thick) is laminated to the matte side of the front and back surfaces (glossy or matte) of the paper using a dry lamination method. • CPP: Base paper (manufactured by Nippon Paper Industries, silver, basis weight 50g / m²) 2 A laminated paper in which CPP (Santox Co., Ltd., EP92, 30 μm thick) is laminated to the matte side of the front and back surfaces (glossy or matte) of the paper using a dry lamination method. • Unstretched PET: RP Topla Co., Ltd., polyester film, NOA CRYSTAL-V (thickness 200 μm). • Stretched PET: Manufactured by Futamura Chemical Co., Ltd., polyester film, FE2001 (thickness 12 μm). • Polyester coating: Base paper (manufactured by Nippon Paper Industries, silver, basis weight 50g / m²) 2 On the matte side of the surface (glossy or matte), apply a polyester-based heat sealant (Unitika Corporation, Elitel KA5071S) at a dry coating rate of 6.0 g / m². 2 Coated paper that has been coated with [a specific material]. • PBS: (Manufactured by Nippon Paper Industries, Silver, Basis weight 50g / m²) 2 A laminated paper in which PBS (Mitsubishi Chemical Corporation, PBSFZ71PM, 25 μm thick) is laminated to the matte side of the front and back surfaces (glossy or matte) of the paper using a dry lamination method.

[0037] [Table 1]

[0038] [Table 2]

[0039] [Table 3]

[0040] As shown in Table 1, when the first seal layer was PHBH only, and the second seal layer was olefin-based, adhesion was not observed (Comparative Examples 1-3). On the other hand, when the second seal layer was polyester-based, the stretched material did not adhere, but the unstretched material showed adhesion, and PBS in particular showed good adhesion (Examples 1-3, Comparative Example 4). Comparing the results in Tables 2 and 3 with EVA added to the results in Table 1 without EVA, the unstretched polyester material showed even higher adhesive strength (Examples 6-8, 11-13). On the other hand, the polyethylene material, which did not adhere without EVA, showed adhesion with the addition of EVA (Examples 4-5, 9-10). Based on the results of material fracture conditions and HS strength tests, particularly in Examples 3, 4, 5, and 10, it was possible to achieve both reduced material fracture and high adhesive strength suitable for practical use. This effectively prevents "material fracture," such as when removing a lid attached to a paper container, where the paper layer peels off. The absence of paper peeling on the container results in a clean, peel-off appearance, prevents exposure of the paper layer surface that absorbs liquid, and enhances the hygiene of the paper container.< / eva> < / phbh>

Claims

1. A first seal layer containing PHBH and a second seal layer are heat-sealed. A packaging body characterized in that the second sealing layer is a polyester-based unstretched resin layer.

2. The packaging according to claim 1, characterized in that the first sealing layer includes EVA.

3. A first seal layer containing PHBH and a second seal layer are heat-sealed. The second sealing layer is a polyethylene-based unstretched resin layer. A packaging body characterized in that the first sealing layer contains EVA.

4. The packaging according to claim 2 or 3, characterized in that the glass transition temperature of the EVA is -50°C or higher and 30°C or lower.

5. The packaging according to claim 1 or 3, characterized in that the first sealing layer and the second sealing layer are provided on different members.

6. The packaging according to claim 1 or 3, characterized in that the first sealing layer and the second sealing layer are provided in different regions of the same member.

7. The packaging according to claim 1 or 3, characterized in that either or both of the first seal layer and the second seal layer are coated layers.

8. The packaging according to claim 1 or 3, characterized in that either or both of the first seal layer and the second seal layer are laminate layers.

9. The packaging according to claim 1 or 3, characterized in that either or both of the first seal layer and the second seal layer are film layers.

10. The packaging according to claim 1 or 3, characterized in that either or both of the first seal layer and the second seal layer are formed on a paper substrate.

Images