JP2015231870A - Lid material and packaging container using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid material having easy openability, no stringiness at seal opening and capable of airtightly sealing a content because of high adhesiveness to a container body despite the use of an environment-friendly plant-derived biomass polyethylene resin, and to provide a packaging container using the lid material.SOLUTION: There is provided an easily openable lid material comprising at least a substrate and a sealant layer. The sealant layer includes a low-density polyethylene resin and a polybutene resin, and the proportion of the low-density polyethylene resin in the sealant layer is 50-90 mass%. The low-density polyethylene resin includes a plant-derived low-density biomass polyethylene resin having a density of 0.910-0.930 g/cmand a melt flow rate (190°C/2.16 kg) of 20-50 g/10 min. The biomass degree of a sealant layer resin composition is 50% or more.

Description

  The present invention relates to a lid material and a packaging container using the lid material. More specifically, it is a cover material having a multilayer structure mainly composed of a thermoplastic resin layer used for cups, trays, etc., and using a plant-derived polyethylene resin reduces the burden on the environment, The present invention relates to a lid that can not only provide easy-openability but also solve problems such as stringing that occurs during opening, and a packaging container that uses the lid.

  Plastic is the main industry of chemical products and has been used in many scenes of daily life. Among various plastic materials, polyethylene is a material excellent in film forming processability, heat sealability, impact resistance, flexibility and the like, and is widely used in various packaging containers such as food and toiletry products.

In recent years, replacement of conventional petroleum-derived plastic materials with carbon-neutral plant-derived plastic materials has been studied due to the increasing awareness of the prevention of global warming and the use of petroleum, which is a depleted resource. If the weight ratio of plant-derived plastic in the product meets the standard of 25% or more, use of the biomass plastic mark is permitted by the Japan Bioplastics Association.

  Plant-derived polyethylene resins were manufactured and sold by Braskem in 2011 with linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) grades and with low-density polyethylene (LDPE) grades in 2014. Yes. The plant-derived LLDPE has an α-olefin having 4 or 6 carbon atoms represented by C4-LLDPE or C6-LLDPE in the side chain. Replacement of conventional petroleum-derived polyethylene with the plant-derived LLDPE and plant-derived HDPE has been studied (see Patent Documents 1 to 5).

  In the food packaging field, packaging forms in which contents are filled in cups or trays such as instant noodles, jelly, and yogurt have been increasing. These cups or trays are generally manufactured using methods such as injection molding and vacuum compression molding of thermoplastic resins such as polystyrene, expanded polystyrene, and polypropylene resin. In consideration of volume and recyclability, paper cups made by laminating polyolefin resin such as polyethylene resin on paper have come to be used, and the contents are not limited to instant noodles, but can be filled with beverages etc. It has become.

  The required quality of the lid material in these cup containers is that the sealant layer, the innermost layer of the lid material, and the container such as a cup as the adherend are strongly bonded to protect the contents. On the other hand, there is a conflicting demand to open with as little force as possible when opening.

  In order to satisfy such requirements, various functions have been imparted to the lid. One of them is the design of the easy opening function, and examples thereof include an interfacial peeling mechanism, an interlayer peeling mechanism, and an agglomerated peeling mechanism.

Among these, the cohesive exfoliation mechanism is designed by blending incompatible or partially compatible thermoplastic resins. The principle of exfoliation is that the cohesive force of the incompatible or partially compatible thermoplastic resin blend layer is small. This is explained by utilizing the cohesive failure of such an incompatible or partially compatible blend layer instead of the interface between the innermost sealant of the lid material and the adherend when opening.

  As a problem of the easy-opening function of the cohesive peeling type, there is a stringing phenomenon in which a resin melted at the time of opening elongates like a thread. This problem requires structural design and morphological design, such as reducing the layer thickness of the thermoplastic resin blend layer or reducing the domain diameter of the matrix-domain structure of the thermoplastic resin blend layer.

  Control of the matrix-domain structure becomes a problem of the interfacial adhesion between the two. When this interfacial adhesion is strengthened (when the domain diameter is reduced), the stringing phenomenon does not occur, but the peel strength increases, and conversely the interfacial adhesiveness. When the diameter is weakened (when the domain diameter is increased), the peel strength is weakened and it is possible to impart easy-openability, but depending on the blend configuration, a stringing phenomenon may occur.

  Known documents are shown below.

JP 2012-167172 A JP 2013-91259 A JP 2013-136589 A JP 2013-151623 A JP 2013-177194 A

  The present invention has been made in view of the circumstances as described above. While using an environmentally friendly biomass polyethylene resin, it is easy to open, has no stringing at the time of opening, and has high adhesion to the container body. A lid capable of sealing an object and a packaging container using the same are provided.

The present invention has been made in view of the problems, and the invention of claim 1
An easily openable lid member provided with at least a base material and a sealant layer, wherein the sealant layer contains a low density polyethylene resin and a polybutene resin, and the proportion of the low density polyethylene resin in the sealant layer is 50% by mass or more and 90 mass% or less, the low-density polyethylene resin comprises low density biomass polyethylene resins derived from plants, wherein the density of the low density biomass polyethylene resin 0.910 g / cm ³ or more, 0.930 g / cm ³ or less The lid material is characterized in that the melt flow rate (190 ° C./2.16 kg) is 20 g / 10 min or more and 50 g / 10 min or less, and the biomass degree of the sealant layer resin composition is 50% or more.

The invention of claim 2 of the present invention is such that the density of the polybutene resin is 0.880 g / cm ³ or more and 0.930 g / cm ³ or less, and the melt flow rate (190 ° C./2.16 kg) is 1 g / 10 min or more, 3 g The lid material according to claim 1, wherein the lid material is / 10 min or less.

  The invention of claim 3 of the present invention is characterized in that the sealant layer resin composition is formed by any one of an extrusion lamination method, a casting method, and an inflation method. It is a cover material of description.

According to a fourth aspect of the present invention, there is provided a melt flow rate of 1 g / g between the substrate and the sealant layer.
The lid material according to any one of claims 1 to 3, further comprising an intermediate layer made of a thermoplastic resin of 10 min or more and 10 g / 10 min or less.

  A fifth aspect of the present invention is the lid according to any one of the first to fourth aspects, wherein the substrate is paper.

  Invention of Claim 6 of this invention is the container main body provided with the accommodating part for accommodating the content, and the opening of this container main body of any one of Claims 1-5. And a lid.

  If the lid | cover material of this invention and a packaging container using the same are used, since a high degree of biomass can be provided, it can be set as an environmentally friendly lid | cover material and packaging container. In addition, even if the lid is incinerated as waste and carbon dioxide is released into the atmosphere, since it contains a lot of plant-derived carbon, an increase in carbon dioxide in the atmosphere can be suppressed. Furthermore, by using paper as a base material, it is possible to further increase the proportion derived from plants, and to increase sustainability.

It is explanatory drawing which showed typically an example of the cover material of this invention in the cross section. It is explanatory drawing which showed typically the other example of the cover material of this invention in the cross section. (A) It is explanatory drawing which showed the packaging container which sealed the cover material of an example of this invention to the opening part of the container main body. (B) It is an enlarged view of the part A of Fig.3 (a).

Hereinafter, embodiments for carrying out the present invention will be described.
FIG. 1 is an explanatory view schematically showing a cross section of an example of the lid of the present invention.
FIG. 2 is an explanatory view schematically showing a cross-section of another example of the lid member of the present invention.

  The lid material of the present invention is an easily openable lid material provided with at least a base material and a sealant layer, and as shown in the cross-sectional view of FIG. 1, a lid material 100 comprising a base material 1 and a sealant layer 2, Or it has the structure like the lid | cover material 200 which consists of the base material 1, the intermediate | middle layer 3, and the sealant layer 2 as shown in sectional drawing of FIG.

  For the substrate 1, a resin film, paper, or the like can be used. In order to increase the biomass degree and reduce the environmental load, it is preferable to select paper as the substrate. The type of paper is not particularly limited.

  The sealant layer 2 is a cohesive peeling type sealant layer made of a resin obtained by blending a low-density polyethylene resin with a polybutene resin. The low density polyethylene resin needs to occupy 50 mass% or more and 90 mass% or less of the sealant layer 2.

  The low density polyethylene resin contains a low density biomass polyethylene resin obtained by synthesizing plant-derived ethylene. The term “derived from a plant” means that it is synthesized using an alcohol obtained by fermenting a plant as a raw material and contains carbon derived from the plant.

As the low-density polyethylene resin that is a component of the sealant layer 2, a polyethylene resin having a density of 0.910 g / cm ³ or more and 0.930 g / cm ³ or less can be preferably used. The low-density biopolyethylene resin obtained by synthesizing plant-derived ethylene contained in the low-density polyethylene resin also has a density of 0.910 g / cm ³ or more and 0.930 g / cm ³ or less. is necessary. If the density is within this range, a cohesive peeling type sea-island structure can be formed with the polybutene resin. More preferably, the density is 0.910 g / cm ³ or more and 0.920 g / cm ³ or less. In the present invention, the density is a value measured according to JIS-K7112.

  The melt flow rate (190 ° C./2.16 kg) of the low density biomass polyethylene resin needs to be 20 g / 10 min or more and 50 g / 10 min or less. In this range, the sealant layer has high fluidity when sealed with a container as a lid material, so that the level difference of the container flange portion can be satisfactorily filled, and the sealing performance as a container is improved. The melt flow rate (MFR) is a value measured according to JIS K 7210.

  The low density polyethylene resin used as the sealant layer 2 includes low molecular weight petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, rosin, and polymerized polymers. Even if rosin such as rosin, hydrogenated rosin, rosin glycerin ester, and hydrogenated product or polymer thereof, or rosin pentaerythritol and hydrogenated product or polymer thereof is used as a tackifier, an appropriate amount may be added to the above resin. I do not care. Other additives may be added as necessary.

  In order to make the relationship between the function as the sealant layer 2 and the easy-openability compatible, it is necessary to mix an appropriate amount of a resin that is completely incompatible or partially compatible with the low-density polyethylene resin.

  As this completely incompatible or partially compatible resin, polybutene resin is optimal. As the polybutene resin, in addition to a homopolymer of 1-butene, a copolymer of 1-butene and an α-olefin such as ethylene, propylene, 1-pentene, 1-hexene can be used, and the polybutene has a melting point. However, by using the one having a temperature of 100 degrees or more, it is possible to prevent the peel strength from being lowered under high temperature and high humidity or hot water filling.

The density of the polybutene resin is desirably 0.880 g / cm ³ or more and 0.930 g / cm ³ or less, and the melt flow rate (190 ° C./2.16 kg) is 1 g / 10 min or more and 3 g / 10 min or less.

  The resin used for the sealant layer is preferably dry blended in advance with a blender such as a tumbler mixer in order to improve the dispersibility of polybutene in polyethylene. Moreover, you may use melt blend suitably for the purpose of stabilizing a dispersion state.

The biomass degree in the present invention is based on the following formula.
Biomass degree (%) = (mass carbon derived from biomass / total carbon mass) × 100
This measurement can be performed by accelerator mass spectrometry (AMS method) by applying a radiocarbon dating method. That is, the ratio of the radioisotope ¹⁴ C in all the carbon elements can be measured and converted.

  The intermediate layer 3 made of a thermoplastic resin provided between the base material 1 and the sealant layer 2 is a layer provided by coextrusion film formation with the sealant layer 2. The low density polyethylene resin used for the sealant layer 2 has a melt flow rate (190 ° C./2.16 kg) of 20 g / 10 min or more and 50 g / 10 min or less, high fluidity, and drawdown (speed at which the molten resin flows from the discharge port). ) Is large, and it is difficult to control the shape for film formation, but the thickness is increased by coextrusion film formation with the intermediate layer 3 made of a thermoplastic resin having a melt flow rate of 1 g / 10 min or more and 10 g / 10 min or less. A uniform sealant layer 2 with no wrinkles can be obtained.

  Examples of the thermoplastic resin of the intermediate layer 3 include low density polyethylene, linear low density polyethylene, acid-modified polyolefin, ionomer, and ethylene-unsaturated carboxylic acid copolymer. For example, when an aluminum foil is used for the barrier layer, an ethylene-acrylic acid copolymer can be used in consideration of adhesiveness with the aluminum foil.

  The thickness of the sealant layer 2 included in the lid member 100 or the lid member 200 of the present invention is preferably 10 μm or more and 40 μm or less. If it is 10 micrometers or more, the level | step difference which can be made in the seal part of a container main body can be filled favorably, and the sealing performance as a packaging container will improve. If it is 40 micrometers or less, there is no possibility that the sealant layer will flow out at the time of heat sealing and impair the appearance of the packaging container.

  Thus, the sealant layer 2 of the lid material satisfactorily fills the step of the opening of the container body by combining the lid material of the present invention and the container body provided with the accommodating portion for accommodating the contents. It can be set as a highly packaging container.

  Fig.3 (a) is explanatory drawing which showed the packaging container which sealed the cover material of an example of this invention to the opening part of the container main body provided with the accommodating part for accommodating the contents. FIG. 3B is an enlarged view of a portion A in FIG.

  For example, as shown in FIG. 3 (a), a container body provided with an accommodating portion for accommodating contents to be adhered is a paper cup 10 in which a low density polyethylene resin is laminated on the inner layer, and the paper cup 10 The lid 100 can be sealed at the opening to form a packaging container.

  The paper cup 10 has a cylindrical body wound with a blank blanked into a fan shape, and seals both overlapping end portions to form a cylindrical laminating portion 11. A material is sealed and attached and sealed, and a top curl portion 12 serving as an opening is provided by curling the upper end portion of the body portion 10 outward.

  A stepped portion h is formed at the upper end portion of the top curl portion 12 due to the influence of the body bonding portion 11 as shown in the partial enlarged view of FIG. When the lid member 100 is sealed to the top curl portion 12, if the melt flow rate of the resin of the heat seal layer 2 is low and the fluidity is small, the stepped portion h becomes a gap and the sealing performance is deteriorated.

  However, the lid 100 of this example uses a resin having a melt flow rate (190 ° C./2.16 kg) of 20 g / 10 min or more and 50 g / 10 min or less for the low density polyethylene resin of the sealant layer 2. When the material 100 is sealed, since the fluidity of the resin in the melted sealant layer is high, the stepped portion h can be filled with the resin in the sealant layer and the sealing performance is improved.

  In addition, since the degree of biomass of the sealant layer is 50% or more, by sealing the lid member 100 or the lid member 200 of the present invention to the opening of the container main body provided with a storage unit for storing the contents, As a whole, the packaging container is environmentally friendly, has an easy-opening property, does not have stringing at the time of opening, and has high adhesion. In particular, by making the container body into a paper cup, the degree of biomass as a packaging container can be increased.

  In addition, the cover material of this invention can make a base material into a multilayer structure. Further, other layers may be provided on the outer layer side or in the middle. In this case, the number of layers may be any number, and a barrier resin layer, an adhesive resin layer, or the like may be laminated as necessary. Moreover, in order to provide barrier property, the vapor deposition film which laminated | stacked the inorganic compound and the metal by methods, such as vapor deposition, can also be used.

  A thermoplastic resin can be used for the adhesion between the layers of the base material having a multilayer structure or the adhesion between the base material and the barrier layer. Plant-derived polyethylene can be used as the thermoplastic resin used for the adhesion. Thereby, higher biomass degree can be achieved as the whole lid | cover material.

  The method for producing the lid material of the present invention can take various methods, but basically, if necessary, a laminated body previously laminated by a technique such as dry lamination or extrusion lamination as a base material, A method of extruding and laminating the thermoplastic resin of the sealant layer 2 is used.

  At that time, when the film thickness is reduced by the cohesive peeling type or when it is made the delamination type, it can also be obtained by laminating by a coextrusion method. Moreover, the film formability can be improved by co-extrusion film formation of the intermediate layer 3 and the sealant layer 2. There are no restrictions on the manufacturing method for these lids.

  The sealant layer resin composition can be formed using an extrusion lamination method, a casting method, or an inflation method.

  Examples and Comparative Examples of the present invention are shown below, but the scope of rights of the present invention is not limited thereto.

(Example 1)
Paper (basis weight 80 g / cm ² ) as the base material and aluminum foil (7 μm) as the barrier layer, plant-derived biomass polyethylene resin (melt flow rate 8.1 g / 10 min (190 ° C./2.16 kg), density 0 The substrate and the barrier layer were laminated by sandwich lamination using 918 g / cm ³ (manufactured by Brasschem).

Thereafter, an ethylene-acrylic acid copolymer (melt flow rate 8 g / 10 min (190 ° C./2.16 kg), density 0.940 g / cm ³ , manufactured by Mitsui DuPont) was used as an intermediate layer for the laminate. , Extrusion lamination by co-extrusion with the resin of the sealant layer, base layer, barrier layer (7 μm), intermediate layer (20 μm) made of thermoplastic resin having a melt flow rate of 1 g / 10 min to 5 g / 10 min, sealant layer The lid material was obtained by laminating in the order of (15 μm).

The sealant layer 2 is 60% by mass of plant-derived low-density biomass polyethylene resin (melt flow rate 30 g / 10 min (190 ° C./2.16 kg), density 0.915 g / cm ³ , manufactured by Braschem) in the entire sealant layer 2. And 40% by mass of polybutene resin (melt flow rate 1.8 g / 10 min (190 ° C./2.16 kg), density 0.915 g / cm ³ , manufactured by Mitsui Chemicals, Inc.).

Separately, for a container main body, a plant-derived low-density biomass polyethylene resin (melt flow rate 3.8 g / 10 min (190 ° C./2.16 kg), density 0.922 g / min) on a paper substrate having a basis weight of 80 g / cm ^2. cm ³ (manufactured by Braschem) was laminated to make a raw material, and a paper cup as shown in FIG. 3 was made using this.

  The lid member was cut in accordance with the top curl portion of the opening of the paper cup to obtain a lid. Using a cup sealer on the flange portion of the paper cup, the lid was sealed under the conditions of a seal temperature of 130 ° C., a seal pressure of 0.15 MPa, and a seal time of 1 second to obtain a packaging container. The leak check liquid confirmed the sealing property in the level | step-difference part h made by the influence of the trunk | drum bonding part of the trunk | drum side surface of a paper cup.

  When the lid was peeled off from the package by hand, it could be peeled off smoothly without stringing. Moreover, the biomass degree of the sealant layer of this cover material is 50% or more.

(Example 2)
Paper (basis weight 80 g / cm ² ) is used as the base material, aluminum foil (7 μm) is used as the barrier layer, and a plant-derived biomass polyethylene resin (melt flow rate 8.1 g / 10 min (190 ° C./min) is used as the adhesive resin layer (15 μm). The base material and the barrier layer were laminated by sandwich lamination using 2.16 kg), density 0.918 g / cm ³ , manufactured by Braskem).

Thereafter, an ethylene-acrylic acid copolymer (melt flow rate 8 g / 10 min (190 ° C./2.16 kg), density 0.940 g / cm ³ , manufactured by Mitsui DuPont) as an intermediate layer with respect to the laminate, Extrusion lamination by coextrusion of the sealant layer resin was performed, and a barrier layer (7 μm), an intermediate layer (20 μm), and a sealant layer (15 μm) were laminated in this order to obtain a lid material.

The sealant layer is made of 70% by mass of a plant-derived low-density biomass polyethylene resin (melt flow rate 30 g / 10 min (190 ° C./2.16 kg), density 0.915 g / cm ³ , manufactured by Braskem), polybutene resin (melt flow) 30% by mass of rate 1.8 g / 10 min (190 ° C./2.16 kg), density 0.910 g / cm ³ , manufactured by Mitsui Chemicals, Inc. is included.

Separately, a container main body, the paper substrate having a basis weight of 80 g / cm ^2, low density biomass polyethylene resins derived from plants (melt flow rate 8.1g / 10min (190 ℃ / 2.16kg ), a density 0.918 g / cm ³ , manufactured by Braskem) was laminated into a raw material, and a paper cup as shown in FIG. 3 was prepared using this.

  The lid member was cut in accordance with the top curl portion of the opening of the paper cup to obtain a lid. A cup sealer was used for the flange portion of the paper cup, and the lid was sealed under the conditions of a seal temperature of 150 ° C., a seal pressure of 0.15 MPa, and a seal time of 1 second to obtain a packaging container.

(Example 3)
The sealant layer is made of 70% by mass of a plant-derived low-density biomass polyethylene resin (melt flow rate 30 g / 10 min (190 ° C./2.16 kg), density 0.915 g / cm ³ , manufactured by Braskem), polybutene resin (melt flow) 30% by mass of 4.0 g / 10 min (190 ° C./2.16 kg), density 0.910 g / cm ³ , manufactured by Mitsui Chemicals, Inc.). Other than that was carried out in the same manner as in Example 1.

Example 4
The sealant layer contains 100% by mass of a plant-derived low-density biomass polyethylene resin (melt flow rate 30 g / 10 min (190 ° C./2.16 kg), density 0.915 kg / cm ³ , manufactured by Braskem). Other than that was carried out in the same manner as in Example 1.

(Comparative Example 1)
For the adhesive resin layer, petroleum-derived polyethylene resin (melt flow rate 7.0 g / 10 min (190 ° C./2.16 kg), density 0.918 g / cm ³ , manufactured by Nippon Polyethylene Co., Ltd.) was used. The sealant layer is made of petroleum-derived polyethylene resin (melt flow rate 35 g / 1
70% by mass of 0 min (190 ° C./2.16 kg), density 0.919 g / cm ³ , manufactured by Ube Maruzen Polyethylene Co., Ltd., polybutene resin (melt flow rate 1.8 g / 10 min (190 ° C./2.16 kg), density 0.910 g / cm ³ , manufactured by Mitsui Chemicals). Other than that was carried out in the same manner as in Example 1.
<Evaluation items>
The following evaluation was performed on Examples 1 to 4 and Comparative Example 1.
(Biomass Degree) Based on the ASTM D6866 method, the concentration of radioactive carbon is determined by an accelerator mass spectrometer (manufactured by National Electrostatics Corporation), so that the biomass of the entire lid material based on the principle of radiocarbon (C14) dating The degree of biomass was evaluated according to the following criteria.
○: Biomass degree is 25% or more ×: Biomass degree is less than 25%

(Sealing)
About the packaging container obtained by the said sealing method, it has arrange | positioned so that a container bottom face part may become upper part, a part of bottom face part was cut open, the leak check liquid was inject | poured, and the sealing performance in the level | step-difference part h was confirmed.
○: Leak is not confirmed ×: Leak is generated (easy opening) In accordance with JIS S0022 6.2, the container is tilted at an angle of 45 ° and fixed to the support table by hand, and the upper surface of the tongue of the container is opened and clamped. The bottle was opened by pulling it straight up at a speed of 500 mm / min, and the maximum value at that time was read as the opening strength. Moreover, the sensory evaluation of the easy opening property at the time of opening by hand was performed.
○: Can be easily opened ×: Not easy to open

(Cobwebbing)
The peeled state of the seal surface after the easy-openability test was visually observed to determine whether or not the stringing phenomenon occurred.
○: No stringing occurs.
X: Yarn drawing occurred.
Table 1 shows the evaluation results of Examples 2 to 4 and Comparative Example 1.

According to the results in Table 1, Example 2 of the present invention satisfies the target biomass degree of 25% or more, has no problem in the sealing property of the packaging container and the lid, can be easily opened, There was no outbreak.
In Example 3, the melt flow rate of polybutene was higher than that in Example 2, but stringing occurred during opening.
In Example 4, polybutene was not used in the sealant. However, compared with Example 2, a large opening strength was required at the time of opening, and the sensory evaluation of easy opening was also poor.
In Example 4, a polyethylene resin derived from petroleum was used as the low density polyethylene resin constituting the cover material, but the sealing performance, easy opening property, and stringing were the same results as in Example 2. The biomass degree as a cover material did not satisfy the target of 25%.

  From the above results, the lid material of the present invention and the packaging container using the same satisfy the biomass degree of 25% or more as the whole lid material, there is no problem in the sealing performance of the lid material and the packaging container, and the lid material is opened. Sometimes it can be easily opened and no stringing occurs. Therefore, this lid material and a packaging container using the same can be suitably used particularly in the field of food packaging.

  The lid | cover material of this invention and a packaging container using the same can be used for food packaging uses, such as instant noodles, jelly, and yogurt.

DESCRIPTION OF SYMBOLS 100, 200 ... Cover material 1 ... Base material 2 ... Sealant layer 3 ... Intermediate layer 10 ... Paper cup 11 ... Body part bonding part 12 ... Top curl part

Claims (6)

An easily openable lid member provided with at least a base material and a sealant layer, wherein the sealant layer contains a low density polyethylene resin and a polybutene resin, and the proportion of the low density polyethylene resin in the sealant layer is 50% by mass or more and 90 mass% or less, the low-density polyethylene resin comprises low density biomass polyethylene resins derived from plants, wherein the density of the low density biomass polyethylene resin 0.910 g / cm ³ or more, 0.930 g / cm ³ or less A lid material, wherein the melt flow rate (190 ° C./2.16 kg) is 20 g / 10 min or more and 50 g / 10 min or less, and the degree of biomass of the sealant layer resin composition is 50% or more. The polybutene resin has a density of 0.880 g / cm ³ to 0.930 g / cm ³ and a melt flow rate (190 ° C./2.16 kg) of 1 g / 10 min to 3 g / 10 min. The lid according to claim 1.   The lid material according to claim 1 or 2, wherein the sealant layer resin composition is formed by any one of an extrusion lamination method, a casting method, and an inflation method.   The lid according to any one of claims 1 to 3, further comprising an intermediate layer made of a thermoplastic resin having a melt flow rate of 1 g / 10 min to 10 g / 10 min between the base material and the sealant layer. .   The said base material is paper, The cover material in any one of Claims 1-4 characterized by the above-mentioned.   It consists of a container main body provided with an accommodating part for accommodating contents, and a lid according to any one of claims 1 to 5 sealed in an opening of the container main body. Packaging container.