JP7484994B2 - Films and packaging bags made from plant-derived polyethylene resin - Google Patents

Description

The present invention relates to a film made of a polyethylene resin composition, and more specifically to a film made of a polyethylene resin composition containing at least one plant-derived polyethylene resin selected from plant-derived high-density polyethylene (HDPE) or plant-derived linear low-density polyethylene (LLDPE), and a packaging bag using this film.

Conventionally, packaging bags, such as pouches used for refilling shampoo and conditioner, and for packaging food, are made of packaging materials consisting of a sealant film and a base film. In order to address environmental issues and the need to conserve exhaustible resources such as petroleum, packaging bags containing biodegradable resins that contain a specified amount of ethylene-α-olefin copolymer and polymers having epoxy groups in polylactic acid resins, which are carbon-neutral materials, with the aim of reducing the amount of petroleum resources used in packaging materials (e.g., Patent Document 1).

JP 2009-155516 A

However, as mentioned above, although such packaging bags contain biodegradable resins other than petroleum-derived materials in the resin composition that constitutes the packaging bag to reduce the proportion of petroleum-derived materials, the bags are significantly inferior to petroleum-based resins in terms of tensile strength, seal strength, stiffness, and other processing suitability, making it difficult to improve productivity.

The object of the present invention is therefore to provide an environmentally friendly film that uses polyethylene resin derived from plants, a renewable resource, as a raw material, thereby conserving petroleum resources and reducing carbon dioxide emissions, as well as a packaging bag that uses said film and has excellent processability.

Another object of the present invention is to provide such a film by extrusion molding using the T-die method.

As a result of various studies, the present inventors have found that the above-mentioned object can be achieved by a film having the following characteristics and a packaging bag using the same.
1. A sealant film having a single layer structure made of a polyethylene resin composition (excluding those having a virgin petroleum-based material content of less than 15% by weight based on the total weight of the film), characterized in that the polyethylene resin composition contains a plant-derived high-density polyethylene and a petroleum-derived polyethylene resin, the plant-derived high-density polyethylene is present in an amount of 5 to 90% by weight and the petroleum-derived polyethylene resin is present in an amount of 10 to 95% by weight based on the total weight of the film, and the plant-derived high-density polyethylene has a biomass ratio of 80 to 100% as calculated from the measurement value of C14 radiocarbon dating.
2. The above sealant film, wherein the plant-derived high-density polyethylene has a density of 941 to 965 kg/ ^m3 .
3. A laminate film comprising any one of the above sealant films laminated on a base film.
4. A packaging bag made using the above laminated film.
5. A packaging bag made using any one of the above sealant films.

Hereinafter, a polyethylene resin composition containing a plant-derived polyethylene resin selected from the above-mentioned plant-derived HDPE or plant-derived LLDPE will be referred to as the "polyethylene resin composition of the present invention."

The present invention reduces the amount of petroleum resources used and suppresses carbon dioxide emissions during the production of a sealant film for packaging materials by blending a plant-derived polyethylene resin into the composition of the sealant film, which currently relies entirely on a petroleum-derived resin composition.
Therefore, it is possible to provide a sealant film for packaging materials that reduces the environmental impact, and it is possible to provide a sealant film for packaging materials that saves petroleum resources and reduces the environmental impact.

FIG. 1 is a flow diagram showing an example of the production of polyethylene derived from sugarcane. 1 is a cross-sectional side view showing a schematic diagram of a single-layer film made of the polyethylene resin composition of the present invention. FIG. 1 is a cross-sectional side view showing a schematic diagram of a film having a multilayer structure having an intermediate layer made of the polyethylene resin composition of the present invention and outer and inner layers made of a petroleum-derived polyethylene resin. 1 is a cross-sectional side view illustrating a schematic diagram of an example of a laminated film of the present invention. FIG. 1 is a perspective view showing a standing pouch as an example of a packaging bag formed using the laminated film of the present invention.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
Containers such as laminated tubes used for food and cosmetics, and packaging bags such as standing pouches widely used as packaging materials for shampoo and conditioner refills, are made of laminated films.

Some of these laminated films are made by laminating a sealant film, which forms the inner surface of the laminated film, onto a base film, and the base film is made of a material such as a polyethylene resin. To form the sealant film, linear low-density or high-density polyethylene is used as the laminate with an intermediate layer sandwiched in between.

Thus, polyethylene resins, which are plastic resins, are often used as materials for laminated films, but these polyethylene resins are produced using petroleum as the starting material. For example, the linear low-density polyethylene mentioned above is produced by copolymerizing ethylene obtained by refining crude oil and an α-olefin, which is a comonomer species, in the gas phase in the presence of a metallocene catalyst at high temperatures, such as 120°C or higher.

Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, ₁ -nonene, 1-decene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, and octadecene, which are represented by the general formula R-CH=CH2 (wherein R is an alkyl group having one or more carbon atoms).

The metallocene catalyst is not particularly limited, but examples include transition metal compounds of Group 4 of the periodic table having a ligand in which one type of group selected from a cyclopentadienyl group, a cyclopentadienyl group having a substituent (a substituted cyclopentadienyl group), an indenyl group, and a substituted indenyl group, and one type of group selected from a fluorenyl group and a substituted fluorenyl group, are bridged by a bridging group.

Representative examples include diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (3-methyl-1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (2,7-dimethyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, and diphenylmethylene ( Metallocene catalysts are used that contain as the main component metallocene compounds such as dichlorides such as 1-indenyl)(9-fluorenyl)zirconium dichloride, diphenylmethylene(4-phenyl-1-indenyl)(9-fluorenyl)zirconium dichloride, and diphenylmethylene(4-phenyl-1-indenyl)(2,7-di-t-butyl-9-fluorenyl)zirconium dichloride, as well as dimethyl, diethyl, dihydro, diphenyl, and dibenzyl forms of the above metallocene compounds.

In addition, examples of the metallocene catalyst include transition metal compounds of Group 4 of the periodic table having a ligand in which one type of group selected from a cyclopentadienyl group, a cyclopentadienyl group having a substituent (substituted cyclopentadienyl group), an indenyl group, and a substituted indenyl group, and one type of group selected from a fluorenyl group and a substituted fluorenyl group, are bridged by a bridging group. Representative examples of such compounds include diphenylmethylene(1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride, diphenylmethylene(3-methyl-1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride, diphenylmethylene(1-cyclopentadienyl)(2,7-dimethyl-9- The main components of the metallocene compounds are dichlorides such as diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (1-indenyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (4-phenyl-1-indenyl) (9-fluorenyl) zirconium dichloride, and diphenylmethylene (4-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, as well as the dimethyl, diethyl, dihydro, diphenyl, and dibenzyl forms of the above metallocene compounds.

However, with the trend toward conserving exhaustible resources such as petroleum and growing awareness of environmental issues such as global warming caused by increased carbon dioxide emissions, petroleum-derived polyethylene resins as described above cannot meet the above trends because large amounts of fixed carbon dioxide contained in the petroleum raw materials are emitted during the process from the manufacture to disposal of petrochemical products.

For these reasons, in recent years, there has been progress in the development of technology to manufacture plastics from plants, which are carbon-neutral and renewable resources. In particular, technology has been established to produce polyethylene, the most commonly used type of plastic, using biomass sugarcane as the starting material (Compiled by the Processing Technology Research Group, Convertec 2009.9, pp. 63-67).
Carbon neutral means that the amount of carbon dioxide absorbed by a plant during growth is approximately equal to the amount of carbon dioxide emitted during combustion.

Fig. 1 is a flow diagram showing an example of the production of sugarcane-derived polyethylene, and Fig. 2 is a cross-sectional side view that typically shows a film made of a polyethylene-based resin composition containing the sugarcane-derived polyethylene-based resin of the present invention.

As shown in Fig. 1, sugar juice extracted from sugarcane harvested from the field is heated, concentrated, and crystallized to separate raw sugar from molasses using a centrifuge. The molasses is then diluted with water to an appropriate concentration and fermented with yeast to produce ethanol.
The bioethanol is heated to produce ethylene through an intramolecular dehydration reaction in the presence of a catalyst, which is then polymerized with a polymerization catalyst to produce polyethylene. It has been confirmed that plant-derived ethylene and polyethylene are of the same quality as petroleum-derived ethylene and polyethylene.

Therefore, the plant-derived polyethylene resin used in the film of the present invention is an LLDPE or HDPE produced from ethylene whose starting material is plant-derived as described above. These can be produced in the same manner as producing a polyethylene resin from petroleum-derived ethylene. That is, plant-derived LLDPE can be produced by copolymerizing plant-derived ethylene and an α-olefin by gas phase polymerization in the presence of a metallocene catalyst.
Furthermore, by polymerizing the plant-derived ethylene in the presence of a Ziegler catalyst or a Phillips catalyst at medium or low pressure, HDPE with fewer branches can be produced.

In the present invention, the plant-derived polyethylene resin obtained as described above is used to produce a film that forms a laminated film constituting a packaging bag, and the proportion of petroleum-derived resin used in the resin composition used in the laminated film is reduced, making it possible to conserve petroleum resources and contributing to environmental improvement by reducing carbon dioxide emissions.
The method for producing this film is not particularly limited, and it can be produced by a conventionally known method.

In the present invention, production by extrusion molding is preferred, and production by extrusion molding using a T-die method is particularly preferred, since it allows for a film to be formed with a uniform thickness, and allows for rapid cooling and rapid film formation, resulting in excellent productivity.

In the present invention, the production of a film by extrusion molding can be carried out, for example, as follows. That is, the resin composition used in the film is dried, and the dried resin composition is supplied to a melt extruder heated to a temperature between the melting point (Tm) of the resin in the resin composition and the melting point + 70°C (Tm + 70), and melted.

Next, the molten resin composition is extruded into a sheet shape using a die such as a T-die, and the resulting sheet-like material is rapidly cooled and solidified using a rotating cooling drum or the like, thereby producing a film.
As the melt extruder, a single screw extruder, a twin screw extruder, a vent extruder, a tandem extruder, etc. can be used depending on the purpose.

In the present invention, a resin composition 1 containing LLDPE or HDPE derived from the above-mentioned sugar cane (not limited to sugar cane, but any plant that is a raw material for the production of polyethylene resins) can be used to form a film F1 as shown in Figure 2.

The sugar cane-derived LLDPE has a density of 910 to 925 kg/ ^m3 and a melt flow rate (MFR) in the range of 2.4 to 8.0 g/10 min., and is an ethylene-α-olefin copolymer of plant-derived ethylene and a plant-derived or petroleum-derived comonomer, and the comonomer may be any α-olefin such as butene-1, hexene-1, or a mixture thereof.

The sugar cane-derived HDPE may have physical properties such as a density in the range of 941 to 965 kg/m ³ and a melt flow rate (MFR) in the range of 2.4 to 8.0 g/10 min.

In the above physical property evaluation, density (d, unit: kg/m ³ ) was measured according to JIS K 6760 (1981) using a sheet having a thickness of 1 mm obtained by press molding at 150°C.

The melt flow rate (MFR, unit: g/10 min) was measured in accordance with JIS K 7210 (1995) at a test temperature of 190°C and a test load of 21.18 N.

In a preferred embodiment, the polyethylene resin composition constituting the film of the present invention contains the above-mentioned plant-derived LLDPE or HDPE in an amount of up to 90% by mass, more preferably 5 to 90% by mass. In one embodiment of the present invention, the above-mentioned polyethylene resin composition contains 5 to 90% by mass of plant-derived LLDPE or HDPE and 10 to 95% by mass of petroleum-derived polyethylene resin.

Furthermore, the polyethylene resin derived from sugar cane has a biomass ratio of 80 to 100% as determined by ^C14 radiocarbon dating.

Here, plant (biomass)-derived resins and petroleum-derived resins do not differ in physical properties such as molecular weight or mechanical and thermal properties. Therefore, the biomass degree is generally used to distinguish between them.

In this biomass, since the carbon of the petroleum-derived resin does not contain ^C14 (radioactive carbon-14, half-life 5730 years), the concentration of this ^C14 is measured by accelerator mass spectrometry and used as an index of the content ratio of plant-derived resin in the resin composition. Therefore, if a film uses a plant-derived resin, the biomass degree of the film can be measured to obtain a biomass degree corresponding to the content of the plant-derived resin.

This biomass degree is measured by burning the sample to generate carbon dioxide, purifying the carbon dioxide in a vacuum line, reducing it with hydrogen using iron as a catalyst to generate graphite, and then mounting this graphite on a tandem accelerator-based ^C14 -AMS dedicated device (manufactured by NEC) to measure the ^C14 count, ^C13 concentration ( ^C13 / ^C12 ), and ^C14 concentration ( ^C14 / ^C12 ), and from these measurements, the ratio of the ^C14 concentration of the sample carbon to the standard modern carbon is calculated.

In this measurement, oxalic acid (HOXII) provided by the National Institute of Standards (NIST) was used as the standard sample.

In the present invention, by using a film made of such a resin composition, instead of using only petroleum-derived resins, this petroleum-derived polyethylene resin is mixed (substituted) with plant-derived polyethylene resin such as sugar cane, which has performance similar to that of petroleum-derived polyethylene resin, thereby making it possible to reduce carbon dioxide emissions during film production and disposal.

In the present invention, by using a plant-derived ethylene-α-olefin copolymer (LLDPE) having a density of 910 to 925 kg/ ^m3 and a melt flow rate of 2.4 to 8.0 g/10 min, or a HDPE having a density of 941 to 965 kg/ ^m3 and a melt flow rate of 2.4 to 8.0 g/10 min, in which the comonomer type is butene-1, hexene-1 or a mixture thereof, as the plant-derived polyethylene resin contained in the polyethylene resin composition 1, a film having physical properties indistinguishable from those of petroleum-derived polyethylene resins can be produced in an existing film production process. Therefore, the raw material can be switched without impairing the processability of the packaging material.

Furthermore, since the resin composition 1 of the present invention has a biomass degree calculated from the measurement value of ^C14 radiocarbon dating, the origin of the raw materials of the polyethylene resin constituting the film can be identified using this biomass degree as an indicator, and the origin of the raw materials from the time of production of the film to the time of disposal can be confirmed.

The plant-derived LLDPE or plant-derived HDPE constituting the film of the present invention preferably has an MFR of 2.4 to 8.0 g/10 min, and more preferably has an MFR of 2.5 to 3.0 g/10 min in order to exhibit a high biomass content and obtain good tensile strength and seal strength for use in packaging bags.
Further, in order to produce a film having a high biomass content and a uniform thickness at high speed by extrusion molding using a T-die method, the MFR is more preferably greater than 4.0, for example, about 4.1 to 8.0 g/10 min.

Next, in the present invention, the above-mentioned resin composition 1 and the petroleum-derived polyethylene resin 2 described below can be used to form a film as follows.

In other words, the film can be constructed as follows (A) or (B) so that the amount of plant-derived polyethylene resin is 5 to 90% by mass and the amount of petroleum-derived polyethylene resin is 10 to 95% by mass relative to the entire film.

First, as shown in FIG. 2, the film F1 of (A) can be made into a single layer structure made of the polyethylene resin composition 1 of the present invention. Here, the polyethylene resin composition 1 of the present invention contains 5 to 90% by mass of a plant-derived polyethylene resin and 10 to 95% by mass of a petroleum-derived polyethylene resin.

As shown in FIG. 3, the film F2 of (B) may have a multi-layer structure having an intermediate layer made of the polyethylene resin composition 1 of the present invention and outer and inner layers made of a petroleum-derived polyethylene resin. Here, the polyethylene resin composition 1 of the present invention contains the plant-derived polyethylene resin at a concentration such that the blend amount of the plant-derived polyethylene resin relative to the entire film is 5 to 90 mass %.

By using such a configuration, the proportion of petroleum-derived polyethylene resin in the polyethylene resin that constitutes the film can be reduced, and carbon dioxide emissions during film production and disposal can be suppressed. In addition, by using petroleum-derived polyethylene resin 2 in the inner and outer layers that constitute film F2 such as (B), film F2 can be manufactured with the properties of existing manufacturing processes. These multi-layer films can be manufactured by co-extrusion molding.

Next, in the present invention, the above films F1 to F2 can be used to make a laminate film. Fig. 4 is a cross-sectional side view showing a typical example of the laminate film, and Fig. 5 is a perspective view showing a standing pouch as an example of a packaging bag formed using the laminate film of the present invention.
As shown in FIG. 4, the laminated film 3 is formed by laminating one of the above films F1 and F2 as a sealant film 4 on a base film 5.

As the base film 5, various resin films or sheets can be used, such as polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polyvinyl chloride resins, fluorine resins, poly(meth)acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as various nylons, polyimide resins, polyamideimide resins, polyarylphthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, acetal resins, and cellulose resins.

By using this type of configuration, it is possible to reduce the proportion of petroleum-derived polyethylene resin that constitutes each film F1 to F2 of the sealant film 4 used for heat sealing, thereby conserving petroleum resources and suppressing carbon dioxide emissions during the manufacture and disposal of the laminated film 3.

Using the laminated film 3 as described above, the sealant film 4 sides of the two side sheets made of the laminated film 3 are arranged facing each other, and a bottom sheet made of a laminate with the sealant film 4 laminated on at least one side is inserted at the lower end of the laminated film 3 by folding it in half at the center with the sealant film 4 side facing outward, forming a gusset section. Near the lower ends on both sides of the folded bottom sheet, roughly semicircular cutouts are provided, and the gusset section is heat sealed at the bottom seal section that is boat-bottom shaped, including the peripheral section, to form the bottom.

Next, the two side edges of the front and back side sheets are heat-sealed at the side edge seals to form the body, and the top end is left as a filling port for the contents, forming a pouch (packaging bag) in a standing pouch format as shown in Figure 5. The top seal provided at the filling port at the top end is used to fill the contents from this part, and then heat seal it, for example by degassing sealing, to seal it. Although not shown, a pouring outlet with a cut line for opening can be formed by laser at the top of the body, etc.

By adopting such a configuration, it is possible to reduce the proportion of petroleum-derived polyethylene resin in the laminate film 3 that constitutes the packaging bag 6, thereby conserving petroleum resources and reducing carbon dioxide emissions during the manufacture and disposal of the packaging bag 6. In particular, since this packaging bag 6 is a refill standing pouch, it is possible to reduce the proportion of petroleum-derived polyethylene resin that constitutes such disposable packaging bags and significantly reduce carbon dioxide emissions.

In addition, films F1-F2 made of the polyethylene resin composition 1 of the present invention and laminated films 3 using these films F1-F2 can be used to produce not only the packaging bags 6 exemplified by the above-mentioned standing pouches, but also laminated tubes for storing contents such as food and beverages, cosmetics, medicines, and miscellaneous goods, containers including liquid paper containers, container lids, and container labels, thereby reducing the proportion of petroleum-derived materials used and significantly reducing carbon dioxide emissions.

Furthermore, in the present invention, the following measures can be taken as means for solving the problems.
1. A film having a single layer structure made of a polyethylene resin composition, or a film having a multi-layer structure including at least one layer made of the polyethylene resin composition, which is extrusion molded by a T-die method, and the polyethylene resin composition is a plant-derived HDPE.
or a plant-derived LLDPE.
2. The film according to item 1 above, wherein the plant-derived polyethylene resin has a melt flow rate (MFR) of 2.4 to 8.0 g/10 min.
3. The film according to 1 or 2 above, characterized in that the plant-derived LLDPE has a density of 910 to 925 kg/ ^m3 , is an ethylene-α-olefin copolymer of plant-derived ethylene and a petroleum-derived comonomer, and the petroleum-derived comonomer is butene-1, hexene-1, or a mixture thereof.
4. The film according to any one of 1 to 3 above, characterized in that it has a biomass degree calculated from the measurement value of ^C14 radiocarbon dating.
5. The film according to any one of 1 to 4 above, characterized in that the blending amount of the plant-derived polyethylene resin is 5 to 90 mass % and the blending amount of the petroleum-derived polyethylene resin is 10 to 95 mass % relative to the entire film, and the film has the following configuration (A) or (B):
(A) A single layer structure made of the polyethylene-based resin composition (B) A multilayer structure having an intermediate layer made of the polyethylene-based resin composition and an outer layer and an inner layer made of a petroleum-derived polyethylene-based resin 6. A laminated film comprising the film according to any one of 1 to 5 above as a sealant film and laminated with a base film.
7. A packaging bag using a laminated film in which the film according to any one of 1 to 5 above is used as a sealant film and is laminated with a base film.
8. The packaging bag according to the above item 7, characterized in that the packaging bag is a refillable standing pouch.

The film of the present invention achieves the following effects by taking measures to solve problems 1 to 8 above.

The film of the present invention contains a plant-derived polyethylene resin selected from plant-derived HDPE or plant-derived LLDPE, and therefore has performance that is indistinguishable from films made of petroleum-derived polyethylene resins. Moreover, it is possible to reduce the amount of petroleum resources used and to suppress carbon dioxide emissions during film production and disposal.
Therefore, it is possible to provide a film made of a polyethylene-based resin with reduced environmental impact. In addition, since the film is extrusion molded by the T-die method, it is possible to provide a film having a uniform thickness and at low cost.

Furthermore, by using a plant-derived polyethylene resin having an MFR of 2.4 to 8.0 g/10 min for the film of the present invention, a homogeneous film can be produced at high speed during extrusion molding by the T-die method.
The plant-derived LLDPE used in the film of the present invention has a density of 910 to 925 kg/ ^m3 and is made of plant-derived ethylene and plant-derived or petroleum-derived butene-1,
By using ethylene-α-olefin copolymers with hexene-1 or mixtures thereof, the film has tensile strength, seal strength and stiffness suitable for packaging bags, for example, standing pouches for refilling, and exhibits excellent processability.
In addition, since the film of the present invention has a biomass degree calculated from the measurement value of C14 radiocarbon dating, the origin of the raw materials of the polyethylene resin that constitutes the film can be identified using this biomass degree as an indicator, making it possible to confirm the origin of the raw materials from the time the film is manufactured to the time it is disposed of.
Therefore, it is possible to provide a film made of a polyethylene resin that allows identification of the origin of the raw materials.
In one embodiment of the present invention, the film of the present invention has a blending amount of the plant-derived polyethylene resin of 5 to 90% by mass and a blending amount of the petroleum-derived polyethylene resin of 10 to 95% by mass relative to the entire film, and has the following configuration (A) or (B):
(A) A single layer structure made of the polyethylene-based resin composition. (B) A multilayer structure having an intermediate layer made of the polyethylene-based resin composition and outer and inner layers made of a petroleum-derived polyethylene-based resin.
Therefore, the proportion of petroleum-derived polyethylene resin in the film can be reduced, reducing the amount of petroleum resources used and suppressing carbon dioxide emissions during film production and disposal.

In addition, by using petroleum-derived polyethylene resin for the inner and outer layers that make up a film like (B), it is possible to manufacture a film with the properties of existing manufacturing processes.

As a result, it is possible to provide a film made of polyethylene resin that conserves petroleum resources and reduces the environmental impact.

In addition, a laminate film formed by laminating the film of the present invention containing a plant-derived polyethylene resin with a base film as a sealant film can reduce the amount of petroleum resources used and suppress carbon dioxide emissions during the production and disposal of the laminate film. Therefore, it is possible to provide a laminate film made of a polyethylene resin that conserves petroleum resources and reduces the environmental burden.

In addition, a packaging bag made using a laminated film in which the film of the present invention containing plant-derived polyethylene resin is used as a sealant film and laminated with a base film can reduce the proportion of petroleum-derived polyethylene resin in the laminated film that constitutes the packaging bag, reducing the amount of petroleum resources used and suppressing carbon dioxide emissions during the manufacture and disposal of the packaging bag. Therefore, it is possible to provide a packaging bag made of polyethylene resin that conserves petroleum resources and reduces the environmental burden.

Furthermore, the packaging bag of the present invention may be a refillable standing pouch, and can reduce the proportion of petroleum-derived polyethylene resin used in the polyethylene-based resin that constitutes the many disposable packaging bags available in the world, thereby reducing the amount of petroleum resources used and suppressing carbon dioxide emissions during the manufacture and disposal of packaging bags. Therefore, it is possible to provide a packaging bag made of polyethylene-based resin that conserves petroleum resources and reduces the environmental burden.

Next, we will explain an example of a film made using the polyethylene resin composition 1 of the present invention.

[Example 1]
Using an extruder with a screw diameter of 30 mm, sugar cane-derived LLDPE C4LL-LL318 (d=0.918, MFR=2.7 g/10 min) manufactured by Braskem was melt-kneaded at 200° C. to obtain a polyethylene resin composition of the present invention.

Then, the resin composition was molded using a T-die cast film-forming machine under processing conditions of an extrusion temperature of 220°C and a rotation speed of 45 rpm, resulting in the production of film F1 shown in Figure 2 with a thickness of 120 μm. The biomass content was measured to be approximately 88%. This film also had a uniform thickness and a beautiful appearance. The butene-1 (C4) comonomer species contained in the sugarcane-derived LLDPE is derived from petroleum, and its content is 1 to 15 mol% (same below).

In contrast, in Comparative Example 1, 100% of petrochemically derived C6LL-Evolu SP2040 (d=0.918, MFR=3.8 g/10 min) manufactured by Prime Polymer Co., Ltd. was used, melt-kneaded at 200°C, and molded into a film having a thickness of 120 μm under processing conditions of an extrusion temperature of 220°C and a rotation speed of 45 rpm in the same manner as in Example 1. The biomass degree was measured to be 0%.

The following physical property evaluation tests were carried out on the resin compositions of Example 1 and Comparative Example 1, and the results are shown below.

As described above, the film of the present invention, which is made of a polyethylene resin composition containing plant-derived LLDPE, has physical properties equivalent to those of a film made only of petrochemical-derived LLDPE, and exhibits good tensile strength, manufacturing processability, and seal strength.

[Test method]
The tensile breaking strength (elongation) was measured using a Tensilon universal testing machine with reference to JIS-Z1702, at a test speed of 500 mm/min. N=3, and a JIS-K7127 test piece type 5 (dumbbell piece: minimum parallel width 6 mm, chuck distance 80 mm).
The waist was measured using a loop stiffness tester with a loop length of 60 mm, a sample width of 15 mm, N=3, and a crushing distance of 17 mm (scale 3).
The seal strength was measured using a heat seal tester TP-701S, by placing 12 μm PET on the evaluation sample, sealing at 180° C. x 1 kgf/cm ² x 1.0 second, cutting out a 15 mm wide rectangular sample, and measuring it with a Tensilon universal testing machine at a test speed of 300 mm/min. N=3.

[Example 2]
Similarly to Example 1, a 30 mm diameter extruder was used to knead and melt sugarcane-derived LLDPE C4LL-LL318 (d=0.918, MFR=2.7 g/10 min) manufactured by Braskem and C6LL-Evolu SP2040 (d=0.918, MFR=3.8 g/10 min) manufactured by Prime Polymer at a mass ratio of 7:3 at 200°C to obtain a polyethylene resin composition of the present invention. Next, the resin composition was molded using a T-die cast film-forming machine under processing conditions of an extrusion temperature of 220°C and a rotation speed of 45 rpm, thereby producing a film F1 having a thickness of 120 μm as shown in FIG. 2.
The biomass content of the film was measured to be about 59%. The film had a uniform thickness and a beautiful appearance, and was excellent in tensile strength, manufacturing processability, and seal strength.

[Example 3]
As in Example 1, a 30 mm diameter extruder was used to knead and melt SHC7260 (d=0.959, MFR=7.2 g/10 min) made by Braskem, which is a sugarcane-derived HDPE, at 200°C to obtain a polyethylene resin composition of the present invention. The resin composition was then molded using a T-die cast film-forming machine under processing conditions of an extrusion temperature of 220°C and a rotation speed of 45 rpm to produce a film F1 shown in FIG. 2 having a thickness of 120 μm. The biomass ratio was measured to be about 95%. This film also had a uniform thickness and a beautiful appearance, and was excellent in tensile strength, manufacturing processability, and seal strength.

[Example 4]
Similarly to Example 1, 50% by mass of Braskem C4LL-LL118 (d=0.916, MFR=1.0 g/10 min), a sugar cane-derived LLDPE, and 50% by mass of Ube Maruzen polyethylene LDPE-F120N (d=0.920, MFR=1.2 g/10 min), a petroleum-derived LLDPE, were melt-kneaded at 200° C. using an extruder with a screw diameter of 30 mm, to obtain a polyethylene resin composition of the present invention.

Then, the resin composition was molded into a film F1 shown in Figure 2 with a thickness of 130 μm using a T-die cast film-forming machine under processing conditions of an extrusion temperature of 200°C and a rotation speed of 60 rpm. The biomass content was measured to be about 44%. In addition, this film had a uniform thickness and a beautiful appearance, and was excellent in tensile strength, manufacturing processability, and seal strength.

[Example 5]
As the resin for the first layer (inner layer) and the third layer (outer layer), Mitsui Chemicals C6LL-EVOLU SP2020 (d=0.916, MFR=2.3g/10min) was melt-kneaded at 200°C using an extruder with a screw diameter of 30mm to prepare a petroleum-derived polyethylene resin. Similarly, as the resin for the second layer (intermediate layer), Braskem's C4LL-LL118 (d=0.916, MFR=1.0g/10min), which is a sugarcane-derived LLDPE, was melt-kneaded at 200°C using an extruder with a screw diameter of 30mm to obtain a polyethylene resin composition of the present invention. The layer thickness ratio of the first layer: the second layer: the third layer was 1:1:1. Next, the resin composition was molded into a film F2 shown in FIG. 3 having a thickness of 130 μm under processing conditions of an extrusion temperature of 200° C. and a rotation speed of 60 rpm using a T-die cast co-extrusion film-forming machine.
The biomass content of the film was measured to be about 29%. The film had a uniform thickness and a beautiful appearance, and was excellent in tensile strength, manufacturing processability, and seal strength.

[Example 6]
As the resin composition for the first layer (inner layer) and the third layer (outer layer), Mitsui Chemicals C6LL-EVOLU SP2020 (d=0.916, MFR=2.3g/10min) was melt-kneaded at 200°C using a 30mmφ extruder with a screw diameter of 30mm to prepare a petroleum-derived polyethylene resin. Similarly, as the resin composition for the second layer (intermediate layer), 50% by mass of Braskem C4LL-LL118 (d=0.916, MFR=1.0g/10min), which is a sugarcane-derived LLDPE, and 50% by mass of Ube Maruzen polyethylene LDPE-F120N (d=0.920, MFR=1.2g/10min) were melt-kneaded at 200°C using a 30mmφ extruder with a screw diameter of 30mm to obtain a polyethylene resin composition of the present invention. The layer thickness ratio of the first layer: the second layer: the third layer was 1:2:1.

Then, the resin composition was molded into a film F2 shown in Figure 3 with a thickness of 130 μm using a T-die cast co-extrusion film-forming machine under processing conditions of an extrusion temperature of 200°C and a rotation speed of 60 rpm. The biomass content of this film was measured to be about 22%. In addition, this film had a uniform thickness and a beautiful appearance, and was excellent in tensile strength, manufacturing processability, and seal strength.

[Example 7]
A biaxially oriented nylon film (ONy, Toyobo Harden N-1102) having a thickness of 25 μm was used as the outer layer as the base film 5, and the film of Example 1 was used. A two-component curing urethane adhesive was used, and the adhesive was applied to the ONy surface at about 4 g/ ^m2 , and the corona-treated surface of the polyethylene was attached by dry lamination to obtain a two-layer laminate film 3 as shown in FIG. 4.
The biomass ratio was measured to be about 70%.

Using this laminated film 3, a refillable standing pouch (packaging bag 6) with a pouring outlet was created, with a laser-scored opening line provided. Contents were placed in this refillable standing pouch, and the opening was sealed. The pouch was observed for leakage of the contents, tipping, buckling, and bending of the body, but no leakage was observed. Furthermore, a drop test was conducted five times from a height of 1m, but no breakage or leakage was observed.

[Example 8]
A biaxially oriented nylon film (ONy, Toyobo Harden N-1102) with a thickness of 25 μm was used as the outer layer as the base film 5, and an aluminum-vapor-deposited surface of VMPET (a metal-vapor-deposited film in which aluminum is vapor-deposited on a polyethylene terephthalate film) with a thickness of 12 μm and aluminum vapor-deposited on one side was used as the intermediate layer. Furthermore, a two-component curing urethane-based adhesive was applied at about 4 g/ ^m2 to the polyethylene terephthalate surface of the VMPET, and this was attached to the corona-treated surface of the film of Example 1 by dry lamination, thereby obtaining a laminated film with a three-layer configuration.

Then, using this laminated film, a refillable standing pouch (packaging bag 6) with a spout and a cut line for opening was created using a laser.
The biomass ratio was measured to be about 62%.
The refillable standing pouches were filled with contents and the tops were sealed, and no leakage, tipping, buckling, or bending of the body was observed. Furthermore, a drop test was conducted five times from a height of 1m, but no breakage or leakage was observed.

[Example 9]
A refillable standing pouch with a pouring spout of Example 8 was prepared using only a petroleum-derived film consisting of oriented polyamide (ONY)/LLDPE (linear low density polyethylene) as the base material. Contents were placed in the refillable standing pouch, and the mouth was sealed. No leakage of contents, tipping, buckling, or bending of the body was observed.
Furthermore, a drop test was conducted five times from a height of 1 m, but no breakage or leakage was observed.
Therefore, the base material of the standing pouch of the present invention may be either a laminated film containing the same plant-derived material as the body portion, or a film derived from petroleum.

As described above in detail, the film made of the polyethylene resin of the present invention is made of resin composition 1 containing plant-derived LLDPE or HDPE obtained by gas phase polymerization. In addition, these films are used as sealant films and laminated with a base film to form laminated films, and packaging bags are made of this laminated film.

This invention can be applied to any product that uses polyethylene resin, such as a film made of polyethylene resin and a packaging bag made of this film.

REFERENCE SIGNS LIST 1 Polyethylene resin composition of the present invention 2 Petroleum-derived polyethylene resin 3 Laminated film 4 Sealant film 5 Base film 6 Packaging bag 7, 8 Side sheet 9 Bottom sheet F1 to F2 Films

Claims (4)

A sealant film having a single layer structure made of a polyethylene resin composition (excluding those having a virgin petroleum-based material content of less than 15% by weight based on the total weight of the film) ,
The polyethylene-based resin composition contains a plant-derived high-density polyethylene and a petroleum-derived polyethylene-based resin,
The blending amount of plant-derived high-density polyethylene is 5 to 85 % by mass based on the entire film,
The blending amount of petroleum-derived polyethylene resin is 15 to 95 mass %,
The plant-derived high-density polyethylene has a density of 941 to 965 kg/m ³ and a melt flow rate (MFR) of 2.4 to 8.0 g/10 min.
The sealant film is characterized in that the plant-derived high-density polyethylene has a biomass content of 80 to 100% as calculated from the measurement value of ^C14 radiocarbon dating. A laminated film comprising the sealant film according to claim 1 laminated with a base film. A packaging bag made using the laminated film according to claim 2. A packaging bag comprising the sealant film according to claim 1.

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