JP7596750B2 - Resin laminate, packaging material, and method for producing resin laminate - Google Patents

Description

The present invention relates to a resin laminate, a packaging material, and a method for producing a resin laminate.

Conventionally, various types of packaging containers have been developed. For example, a known food packaging container is one in which the container is filled with food or the like, and then a lid is heat-sealed to the opening of the container. Plastic containers and lids are often used as materials for constructing such packaging containers.

For example, Patent Document 1 discloses a three-layer coextruded laminate film in which a resin layer made of a resin composition mainly composed of polybutylene succinate, a resin layer made of a resin composition mainly composed of a polyethylene resin, and a resin layer made of a resin composition mainly composed of a polylactic acid resin are coextruded in that order, and discloses an easy-peel sealant in which a resin layer made of a resin composition mainly composed of a polylactic acid resin is used as a sealing layer. Patent Document 2 discloses a sealant film having a base material and a resin layer made of a resin blend of a polyolefin resin, a hydrolyzable thermoplastic resin, and a compatibilizer. Patent Document 2 lists resin films such as PET, NY, and OPP as base materials to be bonded to the sealant layer.

In recent years, from the viewpoint of environmental conservation, there has been an increasing demand to eliminate the use of plastic in such packaging containers. For this reason, consideration has been given to changing some of the packaging containers from plastic containers to paper containers. For example, Patent Document 3 discloses a laminate having a paper base material and a synthetic resin layer containing biomass resin on at least one side of the paper base material, in which the synthetic resin layer is a mixture of biomass resin and synthetic resin, and discloses that this laminate is processed into paper containers such as paper cups and paper piping trays.

JP 2007-320060 A JP 2013-234224 A JP 2008-188812 A

In a packaging container consisting of a main container and a lid, the lid, which has heat-sealing properties, is attached to the opening of the main container to seal it. In this case, the lid is required to have heat-sealing properties and to provide excellent sealing. On the other hand, the lid may also be required to be easy to open. For example, when multiple types of food are packed separately, there may be a mixture of parts where the lid and the main container are firmly attached and easy-to-open properties are not required, and parts where easy-to-open properties are required, and diverse packaging materials, which have become more diverse in recent years, are required to have a variety of functions. In addition, when the contents are packaged in a bag shape (pillow packaging) using a resin laminate with heat-sealing properties, both easy-to-open properties and difficult-to-open properties may be required.

The inventors therefore carried out research aimed at providing a packaging material with two-stage heat sealability that can be made either easy to open (easy peelability) or difficult to open (complete peelability) by controlling the heat sealing conditions.

As a result of intensive research to solve the above problems, the inventors have found that in a resin laminate having a paper base material and a mixed resin layer, by selecting the resin types that make up the mixed resin layer and setting the blending ratio of each resin type within a predetermined range, it is possible to obtain a packaging material that can exhibit two-stage heat sealability, that is, either easy-to-open properties (easy peel property) or difficult-to-open properties (complete peel property).
Specifically, the present invention has the following configuration.

[1] A paper base material and a mixed resin layer provided on at least one side of the paper base material,
The mixed resin layer contains a polyolefin resin and a biomass resin,
The content of the biomass resin is 10 to 49% by mass based on the total mass of the mixed resin layer,
A resin laminate having heat sealability.
[2] The resin laminate according to [1], wherein the polyolefin resin and the biomass resin are substantially uniformly mixed in the mixed resin layer.
[3] The resin laminate according to [1] or [2], wherein the biomass resin is at least one selected from the group consisting of polylactic acid, polybutylene succinate, and polyhydroxyalkanoic acid.
[4] The resin laminate according to any one of [1] to [3], wherein the polyolefin resin is a plant-derived polyolefin resin.
[5] A packaging material comprising the resin laminate according to any one of [1] to [4].
[6] A method for producing the resin laminate according to any one of [1] to [4],
A step of melt-mixing a polyolefin resin and a biomass resin to obtain a resin blend;
and spreading the resin blend on a paper substrate by a coating method or a melt extrusion method.
[7] The method for producing a resin laminate according to [6], wherein the melting temperature in the step of obtaining the resin blend is 180 to 330° C.

According to the present invention, it is possible to obtain a resin laminate that can exhibit two-stage heat sealability, which allows either easy opening (easy peelability) or difficult opening (complete peelability).

FIG. 1 is a cross-sectional view illustrating the configuration of the resin laminate of the present embodiment. FIG. 2 is a cross-sectional view illustrating another configuration of the resin laminate of the present embodiment.

The present invention will be described in detail below. The following explanation of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower and upper limits.

(Resin laminate)
The present invention relates to a resin laminate having heat sealability, which comprises a paper base material and a mixed resin layer provided on at least one side of the paper base material, wherein the mixed resin layer contains a polyolefin resin and a biomass resin, and the content of the biomass resin is 10 to 49% by mass based on the total mass of the mixed resin layer.

Figure 1 is a cross-sectional view illustrating the configuration of the resin laminate of this embodiment. As shown in Figure 1, the resin laminate 100 has a paper substrate 10 and a mixed resin layer 20. An optional layer, as described below, may be provided between the paper substrate 10 and the mixed resin layer 20, but the mixed resin layer 20 may also be provided so as to be in direct contact with the paper substrate 10.

The resin laminate of the present invention has the above-mentioned configuration and can exhibit two-stage heat sealability. In this specification, two-stage heat sealability refers to a property in which either easy-to-open property (easy peel property) or difficult-to-open property (complete peel property) is exhibited depending on the heat sealing conditions. In other words, when heat sealing is performed using a resin laminate having two-stage heat sealability, easy peel property and complete peel property can be used depending on the heat sealing conditions. For example, when heat sealing is performed using a resin laminate having two-stage heat sealability, if the heat sealing temperature is lowered, easy peel property is exhibited, and if the heat sealing temperature is raised, complete peel property is exhibited. In addition, when heat sealing is performed using a resin laminate having two-stage heat sealability, heat sealing can be performed so that easy peel property is exhibited in one part and complete peel property is exhibited in the other part. For example, when heat sealing a container filled with multiple types of food in separate compartments, heat sealing can be performed at the first compartment to provide easy peeling properties, and at the second compartment to provide complete peeling properties.

In this specification, when the resin laminate is heat sealed to an adherend, for example, if the seal strength is less than 7.0 N/15 mm, it can be determined that the laminate has easy peel properties, and if the seal strength is 7.0 N/15 mm or more, it can be determined that the laminate has complete sealability.

The resin laminate of the present invention is also excellent in moisture resistance, and is suitable for use in sealing food, medicine, etc. In this specification, the moisture resistance of the resin laminate can be evaluated by the moisture permeability of the resin laminate. More specifically, the resin laminate is set in a moisture permeability measuring device and the moisture permeability is measured under conditions of 40°C and 90% relative humidity. The moisture permeability of the resin laminate under conditions of 40°C and 90% relative humidity is preferably 50g/ ^m2 / ^24hr or less, more preferably 40g/m2/24hr or less, and even more preferably 30g/ ^m2 /24hr.

Furthermore, the resin laminate of the present invention has a high biomass ratio and contributes to reducing greenhouse gas emissions. Such a resin laminate can be used as a packaging material with reduced environmental impact. The biomass ratio can be calculated by performing a biomass carbon measurement test in accordance with ASTM D 6866 "Standard Test Methods for Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis." The biomass ratio may also be determined by referring to literature values.

The resin laminate of the present invention also has excellent biodegradability because it has a paper base material. Furthermore, by blending a biodegradable biomass resin into the mixed resin layer, it is possible to achieve even better biodegradability.

The overall thickness of the resin laminate is preferably 20 to 300 μm. By keeping the thickness of the resin laminate within the above range, a balance between strength and flexibility can be maintained, making it suitable for packaging applications. In addition, the tensile strength of the resin laminate is preferably 2 N/15 mm or more, more preferably 4 N/15 mm or more, and even more preferably 6 N/15 mm or more. By keeping the tensile strength of the resin laminate within the above range, breakage during packaging can be suppressed.

(Paper base material)
The paper base material contains pulp. Examples of pulp that can be used in this embodiment include wood pulp, cotton, hemp, waste paper pulp, non-wood pulp, etc. Among them, it is preferable to use wood pulp, and examples of wood pulp include coniferous pulp (NKP) and broadleaf pulp (LKP). Examples of non-wood pulp include hemp pulp, kenaf pulp, bamboo pulp, etc. The paper base material used in this embodiment contains 90% by mass or more of pulp. Specifically, examples of the paper base material that can be used include fine paper, glassine paper, coated paper, cast coated paper, and kraft paper.

Among them, it is preferable that the pulp is softwood-derived pulp (NKP). By using softwood-derived pulp (NKP) as the pulp, the strength of the paper base material can be effectively increased. In addition, when printing is performed on the paper base material, hardwood-derived pulp (LKP) may be used in combination to improve printability.

The freeness of the pulp is preferably 300 mlcsf to 600 mlcsf. The freeness of the pulp is the Canadian standard freeness as defined in JIS P 8121-2:2 Pulp - Freeness test method - Part 2: Canadian standard freeness method. By keeping the freeness of the pulp within the above range, the strength of the paper base material can be effectively increased.

The basis weight of the paper substrate is not particularly limited, but is preferably 15 g/m ² or more, more preferably 20 g/m ² or more, and even more preferably 30 g/m ² or more. The basis weight of the paper substrate is preferably 200 g/m ² or less, more preferably 150 g/m ² or less, and even more preferably 100 g/m ² or less. The basis weight of the paper substrate is measured in accordance with JIS P 8124:2011. By setting the basis weight of the paper substrate within the above range, the balance between the strength and flexibility of the resin laminate can be maintained. This makes it easier to impart two-stage heat sealability to the resin laminate.

The thickness of the paper substrate is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more. The thickness of the paper substrate is preferably 250 μm or less, and more preferably 200 μm or less.
It is more preferable that the thickness is 150 μm or less.

The tear strength, burst strength, water resistance, wet strength, etc. of the paper base material can be adjusted as appropriate depending on the packaging application. For example, they can be adjusted as appropriate by using pulp type, freeness, basis weight, internal additives (paper strength agents, wet strength agents, rosin size, alkanol ketene dimer, ASA, etc.).

The paper base material may contain optional components in addition to pulp. Optional components may include, for example, internal sizing agents, external sizing agents, aluminum sulfate, paper strength agents, wet paper strength agents, fixing agents, retention aids, defoamers, fillers, colorants, etc.

(Mixed Resin Layer)
The mixed resin layer contains a polyolefin resin and a biomass resin. In the mixed resin layer, the polyolefin resin and the biomass resin are preferably mixed substantially uniformly. In this specification, when the resin ratios at any 10 points in the mixed resin layer are calculated, if there is no difference of 5 mass% or more in the resin ratios at any 10 points, it can be determined that the polyolefin resin and the biomass resin are substantially uniformly mixed. The resin ratio is determined by infrared spectroscopy, electron microscope observation, or the like.

Examples of polyolefin resins include copolymerized polyolefin resins containing 50 mol% or more of structural units derived from polypropylene, polyethylene, propylene, or ethylene. The polyolefin resin may also be a plant-derived polyolefin resin. For example, the plant-derived polyolefin resin can be obtained as follows. First, starch such as corn or potato or plant-derived cellulose is saccharified and converted into alcohol, and ethylene is synthesized from the alcohol (plant-derived ethylene). Furthermore, propylene is synthesized from plant-derived ethylene (plant-derived propylene), and a polymer is synthesized from monomers such as plant-derived ethylene and plant-derived propylene to obtain a plant-derived polyolefin resin. In this case, the biomass degree of the resin laminate is further increased, which is preferable. Examples of plant-derived polyolefin resins include plant-derived polyethylene resins and plant-derived polypropylene resins.

Examples of biomass resins include polylactic acid, polybutylene succinate, polyhydroxyalkanoic acid, microbially produced polyester, cellulose acetate, polyamide 11, polyamide 610, polyamide 1010, polyamide 1012, etc. Among them, the biomass resin is preferably at least one selected from the group consisting of polylactic acid, polybutylene succinate, polyhydroxyalkanoic acid, and polyamide 11, and polylactic acid is particularly preferred. It is particularly preferred that the biomass resin is a resin having biodegradability.

The content of the biomass resin is 10 to 49% by mass relative to the total mass of the mixed resin layer. The content of the biomass resin may be 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more, relative to the total mass of the mixed resin layer. The content of the biomass resin may be 49% by mass or less, preferably 45% by mass or less, and more preferably 40% by mass or less, relative to the total mass of the mixed resin layer. By setting the content of the biomass resin in the mixed resin layer within the above range, the biomass degree of the resin laminate can be increased while the moisture resistance of the resin laminate can be more effectively increased. Furthermore, by setting the content of the biomass resin in the mixed resin layer within the above range, the resin laminate can exhibit two-stage heat sealability. For example, when heat sealing is performed using the resin laminate, it is possible to selectively use easy peel property and complete peel property, or to selectively use easy peel property and complete peel property partially depending on the heat sealing conditions.

The mixed resin layer may further contain optional components in addition to the polyolefin resin and biomass resin. For example, a compatibilizer can be mentioned as an optional component. Examples of the compatibilizer include hydrogenated styrene butadiene rubber (HSBR), styrene ethylene butylene olefin crystalline block polymer (SEBC), olefin crystalline ethylene butylene olefin block polymer, styrene ethylene butylene styrene block polymer, polyglycerin fatty acid ester synthesized from coconut palm oil, polyethylene glycidyl methacrylate, graft copolymers with a main chain of polyolefin or polycarbonate and a side chain of vinyl polymer, and the like. In addition, examples of commercially available compatibilizers include, for example, Chirabazol manufactured by Taiyo Kagaku, Modiper manufactured by NOF Corp., and Bondfast manufactured by Sumitomo Chemical Co., Ltd. When the mixed resin layer contains a compatibilizer, the content of the compatibilizer is preferably 1% by mass or more, more preferably 3% by mass or more, based on the total mass of the mixed resin layer. In addition, the content of the compatibilizer is preferably 10% by mass or less, more preferably 7% by mass or less, based on the total mass of the mixed resin layer. By including a compatibilizer in the mixed resin layer, the uniform dispersion of the polyolefin resin and the biomass resin is further improved, making it easier to obtain a resin laminate with excellent heat seal properties and moisture resistance.

The basis weight of the mixed resin layer is not particularly limited, but is preferably 5 g/m ² or more, more preferably 8 g/m ² or more, and even more preferably 12 g/m ² or more. The basis weight of the mixed resin layer is preferably 40 g/m ² or less, more preferably 35 g/m ² or less, and even more preferably 30 g/m ² or less. The basis weight of the mixed resin layer is measured in accordance with JIS P 8124:2011. By setting the basis weight of the mixed resin layer within the above range, it becomes easier to impart two-stage heat sealability to the resin laminate. In addition, by setting the basis weight of the mixed resin layer within the above range, the resin laminate becomes easier to exhibit better moisture resistance.

The thickness of the mixed resin layer is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. The thickness of the mixed resin layer is preferably 40 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less.

Other optional components contained in the mixed resin layer include colorants, ultraviolet absorbers, light scattering agents, preservatives, moisture absorbents, antioxidants, fillers, etc.

The mixed resin layer is preferably a layer formed by melt extrusion. That is, the mixed resin layer is preferably a melt-kneaded resin layer. The mixed resin layer may be a single layer, or may have a layer structure in which two or more layers are laminated. For example, the mixed resin layer may be a layer formed by laminating two or more mixed resin layers in which the resin ratio or the ratio of optional components is changed.

(Optional layer)
The resin laminate may have an optional layer in addition to the paper substrate and the mixed resin layer. For example, the resin laminate may have a single resin layer on at least one side of the paper substrate. In this case, the resin laminate is preferably a laminate in which the paper substrate/single resin layer/mixed resin layer are laminated in this order. The single resin layer is preferably a polyolefin resin layer, and examples of the polyolefin resin constituting the single resin layer include polypropylene, polyethylene, copolymerized polyolefin resins having 50 mol% or more of structural units derived from propylene or ethylene. The polyolefin resin constituting the single resin layer may also be a plant-derived polyolefin resin.

Figure 2 is a cross-sectional view illustrating the configuration of the resin laminate 100 including a single resin layer 30. As shown in Figure 2, the resin laminate 100 may have a paper base material 10, a single resin layer 30, and a mixed resin layer 20 in this order. The single resin layer 30 may be provided on both sides of the paper base material 10.

Other optional layers that the resin laminate may have include, for example, an inorganic layer, an anchor layer, an adhesive layer, a printing layer, a decorative layer, a light-shielding layer, etc.

(Method for producing resin laminate)
The present invention also relates to a method for producing the above-mentioned resin laminate. The method for producing the resin laminate includes at least a step of melt-mixing a polyolefin resin and a biomass resin to obtain a resin blend, and a step of spreading the resin blend on a paper substrate by a coating method or a melt extrusion method. Among them, it is preferable to use the melt extrusion method in the step of spreading the resin blend on the paper substrate.

In the process of obtaining the resin blend, the polyolefin resin and the biomass resin are melt-mixed. The melting temperature at this time is preferably 180°C or higher, and more preferably 200°C or higher. The melting temperature is preferably 330°C or lower, more preferably 300°C or lower, and even more preferably 280°C or lower.

Before the step of obtaining the resin blend, a step of dry blending the polyolefin resin and the biomass resin may be carried out. In the dry blending step, it is preferable to mix pellets of the polyolefin resin and pellets of the biomass resin.

After the process of spreading the resin blend on the paper substrate, a process of pressurized cooling is preferably carried out to increase the adhesion between the paper substrate and the mixed resin layer. The cooling temperature in this process is preferably 80°C or less, and more preferably 50°C or less.

In addition, in the method for producing a resin laminate, a step of forming another layer on the paper substrate may be provided before the step of spreading the resin blend on the paper substrate, or a step of subjecting the paper substrate to a surface treatment may be provided.

(Application)
The resin laminate of the present invention is a resin laminate having heat sealability, and therefore can be used as a sealant film (heat seal film). The present invention may also relate to a packaging material including the above-mentioned resin laminate. The packaging material may be made of the above-mentioned resin laminate, or may be made by laminating another layer on the above-mentioned resin laminate. The packaging material may also be made by molding the above-mentioned resin laminate.

The resin laminate of the present invention may also relate to a packaging material used for forming a bag. For example, the resin laminate may be used to package the contents in a bag (pillow packaging) or to caramel package the contents. The resin laminate may also be used to package the contents by sealing on all four sides or three sides.

The features of the present invention will be described in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. In the following, Examples 1 to 7 shall be read as Reference Examples 1 to 7, respectively.

Example 1
75 parts by mass of pellets of Novatec LD LC520 (manufactured by Japan Polyethylene, MFR 3.6 g/10 min (JIS K 6922-2 temperature 190 ° C. load 2.16 kg), density 0.923 g/cm ³ , melting point 111 ° C.), which is a low density polyethylene (LDPE) as a polyolefin resin, and 25 parts by mass of pellets of Luminiy PLA L-175 (manufactured by Total Corbion PLA, MFR 4.5 g/10 min (temperature 190 ° C. load 2.16 kg), density 1.25 g/cm ³ , melting point 170 ° C., biomass degree 100%), which is a polylactic acid as a biomass resin, were dry blended, and then kneaded with a twin-screw melt mixer to obtain mixed pellets. The kneading temperature was 220 ° C. The obtained mixed pellets were fed into an apparatus equipped with a single-screw extruder and a T-die, and melt-extruded at 300°C into a film having a thickness of 20 μm. This was then laminated onto a paper substrate (unbleached kraft paper manufactured by Oji Materia, basis weight 70 g/ ^m2 ) and pressure was applied with a nip roll to a cooling roll (temperature 20°C) to obtain a resin laminate.

Example 2
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 90 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 10 parts by mass.

Example 3
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 80 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 20 parts by mass.

Example 4
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 65 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 35 parts by mass.

(Example 5)
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 55 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 45 parts by mass.

Example 6
A resin laminate was obtained in the same manner as in Example 1, except that a polybutylene succinate resin, BioPBS F791 (manufactured by Mitsubishi Chemical, MFR 5 g/10 min (temperature 190° C., load 2.16 kg), density 1.26 g/cm ³ , melting point 115° C., biomass degree 50%), was used instead of Luminiy PLA L-175.

(Example 7)
A resin laminate was obtained in the same manner as in Example 1, except that semi-crystalline PHA, a polyhydroxyalkane (manufactured by CJ BIO, MFR 10 g/10 min (temperature 190°C, load 2.16 kg), density 1.23 g/cm ³ , melting point 119°C, biomass degree 100%) was used instead of Luminiy PLA L-175.

(Example 8)
A resin laminate was obtained in the same manner as in Example 1, except that SBC818 (manufactured by Braskem, MFR 8 g/10 min (temperature 190° C., load 2.16 kg), density 0.916 g/cm ³ , melting point 108° C., biomass degree 95%), a plant-derived polyethylene (bio-PE), was used instead of Novatec LD LC520.

(Comparative Example 1)
Pellets of Novatec LD LC520 were fed into an apparatus equipped with a single screw extruder and a T-die, and melt-extruded into a film having a thickness of 20 μm. At the same time, this was laminated onto a paper substrate (unbleached kraft paper manufactured by Oji Materia, basis weight 70 g/ ^m2 ), and pressure was applied with a nip roll to a cooling roll (temperature 20°C) to obtain a resin laminate.

(Comparative Example 2)
Pellets of Luminiy PLA L-175 were fed into an apparatus equipped with a single screw extruder and a T-die, and melt-extruded into a film having a thickness of 20 μm. At the same time, the film was laminated onto a paper substrate (unbleached kraft paper manufactured by Oji Materia, basis weight 70 g/ ^m2 ), and pressure was applied with a nip roll to a cooling roll (temperature 20°C) to obtain a resin laminate.

(Comparative Example 3)
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 95 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 5 parts by mass.

(Comparative Example 4)
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 40 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 60 parts by mass.

(Comparative Example 5)
A resin laminate was obtained in the same manner as in Example 1, except that the blending amount of the Novatec LD LC520 pellets was changed to 25 parts by mass, and the blending amount of the Luminiy PLA L-175 pellets was changed to 75 parts by mass.

(evaluation)
<Moisture permeability>
The resin laminates obtained in the Examples and Comparative Examples were set in a moisture permeability measuring device (L80-4000, manufactured by LYSSY Co., Ltd.) and the moisture permeability was measured under conditions of 40° C. and a relative humidity of 90%.

<Heat seal strength>
The resin layers of the resin laminates obtained in the Examples and Comparative Examples were stacked on top of each other and set in a heat seal tester (TP701B, manufactured by Tester Sangyo Co., Ltd.) and laminated at a sealing temperature of 140°C or 170°C. The lamination conditions were 0.55 MPa for 1 second. The laminated product obtained was then cut to a width of 15 mm, and the T-peel strength was measured using a Tensilon, and this T-peel strength was taken as the heat seal strength. In Table 1, if the seal strength was less than 7.0 N/15 mm, it was evaluated as having easy peelability (peeling at the interface of the resin layer), and if the seal strength was 7.0 N/15 mm or more, it was evaluated as having complete sealability (paper substrate material breakage).

<Biomass ratio>
The biomass degree is the biomass degree relative to the total resin, and was calculated from the biomass degree of each biomass resin.

In the resin laminate obtained in the examples, when the heat sealing temperature was 140°C, the seal strength was less than 7.0 N/15 mm, so easy peel properties were exhibited, and when the heat sealing temperature was 170°C, the seal strength was 7.0 N/15 mm or more, so complete peel properties were exhibited. Thus, the resin laminate obtained in the examples had two-stage heat sealability (the property of being able to selectively use easy peel properties and complete peel properties depending on the heat sealing conditions). In addition, the resin laminate obtained in the examples had a high biomass degree and excellent moisture resistance.

10 Paper base material 20 Mixed resin layer 30 Single resin layer 100 Resin laminate

Claims (5)

A paper base material and a mixed resin layer provided on at least one surface side of the paper base material,
The mixed resin layer contains a polyolefin resin and a biomass resin,
The polyolefin resin is a plant-derived polyethylene,
The biomass resin is at least one selected from the group consisting of polylactic acid, polybutylene succinate, polyhydroxyalkanoic acid, and polyamide 11;
The content of the biomass resin is 10 to 49% by mass based on the total mass of the mixed resin layer,
When the mixed resin layers are overlapped and heat-sealed at a heat sealing temperature of 140°C, the seal strength is less than 7.0 N/15 mm, and when the mixed resin layers are overlapped and heat-sealed at a heat sealing temperature of 170°C, the seal strength is 7.0 N/15 mm or more . The resin laminate according to claim 1, wherein the polyolefin resin and the biomass resin are mixed substantially uniformly in the mixed resin layer. A packaging material comprising the resin laminate according to claim 1 or 2 . A method for producing the resin laminate according to claim 1 or 2 ,
A step of melt-mixing a polyolefin resin and a biomass resin to obtain a resin blend;
and spreading the resin blend on a paper substrate by a coating method or a melt extrusion method. The method for producing a resin laminate according to claim 4 , wherein the melting temperature in the step of obtaining the resin blend is 180 to 330°C.

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