synthetic resin bags

Abstract

This invention provides an environmentally friendly synthetic resin bag with a simple construction that has the same strength as conventional products made from polyethylene. [Solution] The synthetic resin bag 100 of the present invention is made using a resin film 50 made of a resin composition 10 which contains at least high-density polyethylene (HDPE), oyster shell powder (calcium carbonate), and linear low-density polyethylene (metallocene LLDPE) synthesized with a metallocene catalyst, and which contains 50-80 wt% high-density polyethylene (HDPE) pellets 11, 5-15 wt% oyster shell component-containing pellets 12, and 15-35 wt% linear low-density polyethylene (metallocene LLDPE) pellets 13 as raw materials. The oyster shell component-containing pellets preferably contain at least 9.7-29.7 wt% high-density polyethylene 1, 70-90 wt% oyster shell powder 2, and 0.3 wt% zinc powder 3.

Description

Technical Field

[0001] The present invention relates to a synthetic resin bag, and more particularly to an environmentally friendly synthetic resin bag in terms of disposal after use.

Background Art

[0002] When purchasing goods at a store, it is common practice to carry the goods home in a synthetic resin bag called a cash register bag for easy carrying. In addition, cash register bags are also used as garbage bags for storing and disposing of unnecessary items such as packaging materials for purchased goods.

[0003] By the way, cash register bags (garbage bags) after disposal are finally incinerated. Generally, cash register bags are manufactured using synthetic resins such as polyethylene as raw materials. However, synthetic resin bags made from fossil resources have a high calorific value when incinerated, which can damage the incinerator and shorten its lifespan. At the same time, carbon dioxide (CO2) generated during incineration contributes to environmental problems such as global warming. Moreover, cash register bags are products that are consumed in large quantities, and measures to address the environment are required.

[0004] Therefore, as an environmental measure for cash register bags, synthetic resin bags made from biopolyethylene produced from renewable resources such as sugarcane are widely and generally known. Synthetic resin bags using biopolyethylene can significantly reduce the dependence on fossil resources and, by using plant-derived materials as raw materials, can reduce the environmental impact throughout the product life cycle. However, it has to be said that biopolyethylene is inferior in the productivity of basic raw materials and is not suitable for products such as cash register bags and garbage bags that are consumed in large quantities.

[0005] On the other hand, in order to reduce CO2 emissions during manufacturing and combustion, cash register bags and garbage bags in which calcium carbonate is blended with polyethylene as a raw material are also known. However, when calcium carbonate is added to shopping bags or garbage bags, their strength decreases compared to bags without calcium carbonate, making them more prone to tearing. Therefore, in order to obtain a product with the same strength as conventional bags (bags without calcium carbonate), the amount of polyethylene resin, which emits CO2, must be increased.

[0006] Therefore, a bio-resin film has been proposed that uses a marine bio-resin composition as a raw material, comprising a bio-derived component, a polyolefin resin component, and a reinforcing agent, wherein the bio-derived component is a marine organism-derived component nanofine to 30 μm or less, the marine organism-derived component is finely ground seashells and / or crustacean shells, the proportion of the marine organism-derived component in the solid content is 25% by mass or more, and the reinforcing agent has reinforcing agent particles nanofine to 1 nm to 50 nm, and the reinforcing agent particles include iron oxide particles. It is known that shopping bags and garbage bags are manufactured using this bio-resin film (see, for example, Patent Document 1).

[0007] The shopping bags (garbage bags) manufactured based on this Patent Document 1 require less polyolefin resin to obtain a product with the same strength as conventional products, thus being environmentally friendly. However, Patent Document 1 uses reinforcing agent particles containing iron oxide particles, which are nano-sized to 1 nm to 50 nm, as the reinforcing agent. The configuration is limited and can be considered cumbersome. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 7674712 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] This invention was made in view of the above circumstances, and aims to provide an environmentally friendly synthetic resin bag with a simple structure that has the same strength as conventional products made from polyethylene. [Means for solving the problem]

[0010] To achieve the above objective, a first aspect of the present invention is a synthetic resin bag characterized by being made using a resin film made from a resin composition comprising at least high-density polyethylene (HDPE), calcium carbonate, and linear low-density polyethylene (metallocene LLDPE) synthesized with a metallocene catalyst. In this case, calcium carbonate should be replaced with oyster shell powder.

[0011] Furthermore, the resin film may comprise a first resin layer made of a resin composition containing at least the high-density polyethylene (HDPE), the oyster shell powder, and the linear low-density polyethylene (metallocene LLDPE), and a second resin layer made of a resin composition containing at least the high-density polyethylene (HDPE) and the linear low-density polyethylene (metallocene LLDPE). In this case, the resin film preferably has a three-layer structure in which the first resin layer is used as an intermediate layer, and one side and the other side of the first resin layer are sandwiched between the second resin layer.

[0012] Furthermore, a second aspect of the present invention is a synthetic resin bag made using a resin film made from a resin composition containing at least high-density polyethylene (HDPE) pellets, oyster shell component-containing pellets including high-density polyethylene (HDPE), oyster shell powder, and zinc powder, and linear low-density polyethylene (metallocene LLDPE) pellets synthesized with a metallocene catalyst as raw materials.

[0013] In this case, the resin composition may contain 50-80 wt% of the high-density polyethylene (HDPE) pellets, 5-15 wt% of the oyster shell component-containing pellets, and 15-35 wt% of the linear low-density polyethylene (metallocene LLDPE) pellets. Furthermore, the oyster shell component-containing pellets may contain 9.7 to 29.7 wt% of high-density polyethylene (HDPE), 70 to 90 wt% of oyster shell powder, and 0.3 wt% of zinc.

[0014] Furthermore, the resin composition may further contain titanium dioxide (TiO2). Furthermore, the resin composition may further contain barium sulfate (BaSO4). Furthermore, the aforementioned synthetic resin bag may be provided with a handle on the opening side. [Effects of the Invention]

[0015] The synthetic resin bag according to this invention aims to reduce CO2 emissions during manufacturing and combustion by using calcium carbonate, and to suppress the decrease in strength caused by using calcium carbonate by using linear low-density polyethylene (metallocene LLDPE) synthesized with a metallocene catalyst. Therefore, an environmentally friendly synthetic resin bag with the same strength as conventional products using polyethylene as a raw material can be provided with a simple structure. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram illustrating a simplified method for manufacturing a synthetic resin bag according to the present invention. [Figure 2] This is an enlarged schematic diagram illustrating the structure of another synthetic resin bag according to the present invention. [Figure 3] This is a schematic diagram illustrating a simplified method for manufacturing another synthetic resin bag according to the present invention. [Figure 4] This is a schematic diagram showing yet another synthetic resin bag according to the present invention. [Modes for carrying out the invention]

[0017] Hereinafter, an example of an embodiment of a synthetic resin bag according to the present invention will be described based on the drawings. Note that the embodiments described below are preferred specific examples of the present invention, and thus are technically limited in various ways. However, the scope of the present invention is not limited to these embodiments unless specifically limited in the following description.

[0018] <First Embodiment> As shown in FIG. 1, the synthetic resin bag 100 in the present embodiment uses high-density polyethylene (HDPE) used in the production of conventional plastic shopping bags and garbage bags as a base resin as a production raw material, and oyster shell powder 2 is blended therein as a calcium carbonate component, and a resin film 50 made of a resin composition 10 having a configuration in which linear low-density polyethylene (metallocene LLDPE) synthesized by a metallocene catalyst is blended is used for bag making. In FIG. 1, a synthetic resin bag 100 provided with a pair of handles (handheld portions) 102, 102 on the left and right in the width direction on the opening side of the storage portion 101 is shown.

[0019] That is, the synthetic resin bag 100 manufactures the synthetic resin film 50 using a polyolefin resin component (HDPE and metallocene LLDPE) and oyster shell powder 2, and uses this synthetic resin film 50 for bag making. The polyolefin resin component is provided by using high-density polyethylene (HDPE) pellets 11 and linear low-density polyethylene (metallocene LLDPE) pellets 13.

[0020] This metallocene LLDPE is a polymer polymerized using a metallocene catalyst and is a type of linear low-density polyethylene (LLDPE). Also known as metallocene polyethylene, it possesses high strength characteristics, being resistant to tensile, tearing, and puncture, and less prone to breakage. Therefore, linear low-density polyethylene (metallocene LLDPE) is used as a reinforcing component to compensate for the decrease in physical properties caused by the inclusion of oyster shell powder 2 and maintain practical strength. Furthermore, while increasing the blending ratio of metallocene LLDPE improves tear resistance, impact resistance, and elongation (toughness), it reduces stiffness (rigidity), requiring consideration of blocking and processing stability depending on the conditions.

[0021] Since oyster shell powder 2 cannot be used to produce bags if it remains in powder form, it is provided by mixing it with high-density polyethylene (HDPE) 1 and zinc powder 3, and using oyster shell component-containing pellets 12, which are resin pellets in which the oyster shell powder 2 is dispersed.

[0022] This oyster shell component-containing pellet 12 is a masterbatch containing, for example, 9.7-29.7 wt% high-density polyethylene (HDPE) 1, 70-90 wt% oyster shell powder 2, and 0.3 wt% zinc powder. In this case, it is desirable to use oyster shell powder 2 that has been nano-finely ground to a size of 30 μm or less.

[0023] Because such oyster shell powder 2 is abundant, it can be easily and inexpensively obtained and is useful as a basic raw material for products that are consumed in large quantities, such as shopping bags and garbage bags. Furthermore, oyster shell powder 2 is said to reduce CO2 emissions during the manufacturing and combustion of synthetic resin bags 100.

[0024] Therefore, the synthetic resin bag 100 is manufactured by producing a synthetic resin film 50 using a resin composition 10 that contains at least high-density polyethylene (HDPE) pellets 11, oyster shell component-containing pellets 12, and linear low-density polyethylene (metallocene LLDPE) pellets 13 as manufacturing raw materials (compounds), and then making the bag using this synthetic resin film 50.

[0025] The synthetic resin film 50 can be manufactured, for example, from a resin composition 10 which contains 50-80 wt% high-density polyethylene (HDPE) pellets 11, 5-15 wt% oyster shell component-containing pellets 12, and 15-35 wt% linear low-density polyethylene (metallocene LLDPE) pellets 13. The synthetic resin bag 100 has no particular restrictions on its thickness and can be manufactured using a synthetic resin film 50 with a thickness of approximately 8 to 50 μm, similar to conventional synthetic resin bags.

[0026] Furthermore, the synthetic resin film 50 may also contain titanium dioxide (TiO2) or barium sulfate (BaSO4). That is, because oyster shells contain a protein called conchiolin, the synthetic resin film 50 may burn at the processing temperature and turn yellow. Therefore, it is preferable to include titanium dioxide (TiO2), barium sulfate (BaSO4), or both, for the purpose of whitening.

[0027] Furthermore, titanium dioxide (TiO2) not only has a whitening effect but also a deodorizing effect. Therefore, it is desirable to include it for the purpose of suppressing odors generated during the processing of the synthetic resin film 50. Therefore, by adding titanium dioxide (TiO2) and barium sulfate (BaSO4) to the compound, discoloration and odor generated by heating during the bag-making process of the synthetic resin bag 100 can be prevented.

[0028] Next, a method for manufacturing the synthetic resin bag 100 will be described. Such a synthetic resin bag 100 can be manufactured in the same way as a typical shopping bag (T-shirt type) made of polyethylene resin, for example, as follows.

[0029] (1) Weighing and pre-mixing of raw materials High-density polyethylene (HDPE) pellets 11, oyster shell component-containing pellets 12, and linear low-density polyethylene (metallocene LLDPE) pellets 13 are weighed in the arbitrary mixing ratios described above and dry-mixed in a weighing mixer (blender). Mixing is basically carried out at room temperature and homogenized in a few minutes.

[0030] (2) Film forming (inflation / blow) The mixed raw materials are supplied from the hopper to an extruder (single-screw), where they are melted and kneaded to form a single mass. The mass is then extruded through an annular die into a tube shape, inflated with air (bubble molding), cooled, taken up, and wound up to form a synthetic resin film 50. At this time, both opposing ends are folded inward (pushed in) to a predetermined width and then wound up.

[0031] In this process, the optimal cylinder temperature range varies depending on the resin grade and equipment specifications, but it is generally adjusted within a range of approximately 170-220°C. The residence (mixing) time also varies depending on the screw, rotation speed, and discharge volume, but it is generally adjusted to a range of several tens of seconds to several minutes, while monitoring bubble stabilization, gel reduction, and physical properties.

[0032] (3) Bag making process The rolled synthetic resin film 50 is printed as needed, then slit (width-cut), punched out handles, and sealed (heat-sealed). After that, each sheet is cut into a synthetic resin bag 100, and the predetermined number of bags are bundled together.

[0033] Furthermore, in the manufacture of the synthetic resin bag 100, a compatible additive may be used to suppress phase separation and processability issues caused by the incorporation of oyster shell powder 2. In addition, a slip agent or anti-blocking agent may be added to improve opening (suppress blocking). Antistatic agents and colorants may also be added. Furthermore, the presence or absence and conditions of corona discharge treatment may be adjusted to improve printability.

[0034] <Second Embodiment> Furthermore, in this invention, the film-forming process may involve manufacturing a two-layer, three-layer structure, for example. In other words, it differs from the first embodiment described above in that the synthetic resin film has a multilayer structure.

[0035] In the other embodiments described below, the focus will be on the differences from the first embodiment described above. Therefore, components similar to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted. Unless otherwise specified, they will be considered identical.

[0036] As shown in Figure 2, the synthetic resin bag 200 of this embodiment is made from a three-layer synthetic resin film 60 in which a resin layer 60-1 containing oyster shell powder 2 is sandwiched between resin layers 60-2 that do not contain oyster shell powder 2.

[0037] In other words, as shown in Figure 3, the synthetic resin bag 200 is made by preparing a resin composition 10 containing oyster shell powder 2 and a resin composition 20 not containing oyster shell powder 2, respectively, and in the film formation process, a first resin layer 60-1 made of resin composition 10 is used as an intermediate layer, and one side and the other side of the first resin layer 60-1 are sandwiched between a second resin layer 60-2 made of resin composition 20 to form a three-layer synthetic resin film 60 into which the bag is made. Figure 3 shows a synthetic resin bag 200 with a pair of handles (carrying parts) 202, 202 on the left and right sides in the width direction on the opening side of the storage section 201.

[0038] As described in the first embodiment above, resin composition 10 is prepared using high-density polyethylene (HDPE) pellets 11, oyster shell component-containing pellets 12, and linear low-density polyethylene (metallocene LLDPE) pellets 13 as raw materials (compounds). Resin composition 20 is prepared using only high-density polyethylene (HDPE) pellets 11 and linear low-density polyethylene (metallocene LLDPE) pellets 13 as raw materials (compounds).

[0039] In this three-layer synthetic resin bag 200, both the inner second resin layer 60-2 and the outer second resin layer 60-2 do not contain oyster shell powder 2, resulting in a feel and texture that is indistinguishable from conventional synthetic resin bags. Therefore, stable processing can be performed, similar to conventional synthetic resin bags.

[0040] <Third Embodiment> Furthermore, in this invention, the handles (carrying parts) may be provided near the center of the front and back of the bag, rather than on the left and right sides in the width direction of the bag, as in the first and second embodiments described above. Figure 4 is a schematic diagram showing yet another synthetic resin bag according to the present invention.

[0041] As shown in Figure 4, the synthetic resin bag 300 of this embodiment is manufactured using high-density polyethylene (HDPE) pellets 11, oyster shell component-containing pellets 12, and linear low-density polyethylene (metallocene LLDPE) pellets 13, similar to the resin composition 10 described in the first embodiment above. Near the opening edge of the storage section 301, horizontally elongated oval openings 302 are provided on the front and back, respectively, and a pair of handles (carrying parts) 303, 303 are provided. In this case, the openings 302 forming the handles 303 should be large enough to allow fingers from the index finger to the little finger to be inserted together.

[0042] <Fourth Embodiment> Furthermore, although not shown in the figures, in this invention, the storage section and the handle (carrying section) are not integrated, as in the first to third embodiments described above. Instead, the storage section may consist only of a storage section without a handle (carrying section).

[0043] In other words, similar to the resin composition 10 described in the first embodiment above, a synthetic resin film is manufactured using a resin composition that includes at least high-density polyethylene (HDPE) pellets 11, oyster shell component-containing pellets 12, and linear low-density polyethylene (metallocene LLDPE) pellets 13 as manufacturing raw materials (compounding components), and a so-called garbage bag is manufactured using this synthetic resin film, which does not have a handle (carrying part) near the opening edge of the storage section.

[0044] Therefore, according to this embodiment, even when using oyster shell powder that would otherwise be discarded, by incorporating linear low-density polyethylene (metallocene LLDPE) synthesized with a metallocene catalyst, it is possible to produce synthetic resin bags (shopping bags and garbage bags) that have the same strength as conventional shopping bags and garbage bags manufactured using synthetic resins such as polyethylene as raw materials, without increasing the amount of petroleum-derived resin.

[0045] In other words, since it does not require the use of special raw materials with a limited composition, it can be easily manufactured into bags without any hassle. Therefore, we can provide an environmentally friendly synthetic resin bag that reduces waste (oyster shells), reduces the use of petroleum-derived raw materials, and reduces CO2 emissions during disposal after use.

[0046] Although this embodiment has been described above, the above-described embodiment is merely an example to facilitate understanding of the present invention and is not intended to limit its interpretation. Furthermore, the present invention is not limited to the above-described embodiment, and any modifications, improvements, etc., to the extent that they can achieve the objective of the present invention are included in the present invention. [Explanation of Symbols]

[0047] 1.11 High-density polyethylene (HDPE) pellets 2. Oyster shell powder (calcium carbonate) 3. Zinc powder 10,20 Resin composition 12. Oyster shell component-containing pellets 13 Linear low-density polyethylene (metallocene LLDPE) pellets 50, 60 Synthetic resin film 100,200 synthetic resin bags (shopping bags) 101,201,301 Storage Units 102,202,303 Handles 300 synthetic resin bags (shoddy bags)

Claims

1. High-density polyethylene (HDPE) and Calcium carbonate and Linear low-density polyethylene (metallocene LLDPE) synthesized with a metallocene catalyst, A synthetic resin bag characterized by being manufactured using a resin film made from a resin composition containing at least [a certain substance].

2. The synthetic resin bag according to claim 1, characterized in that the calcium carbonate is oyster shell powder.

3. The aforementioned resin film is A first resin layer comprising a resin composition containing at least the high-density polyethylene (HDPE), the oyster shell powder, and the linear low-density polyethylene (metallocene LLDPE), A second resin layer comprising a resin composition containing at least the high-density polyethylene (HDPE) and the linear low-density polyethylene (metallocene LLDPE), The synthetic resin bag according to claim 2, characterized by having the following features.

4. The aforementioned resin film is The first resin layer is used as an intermediate layer, and the first resin layer is sandwiched between the second resin layer, forming a three-layer structure. The synthetic resin bag according to feature 3.

5. High-density polyethylene (HDPE) pellets and Pellets containing oyster shell components, including high-density polyethylene (HDPE), oyster shell powder, and zinc powder, Linear low-density polyethylene (metallocene LLDPE) pellets synthesized with a metallocene catalyst, A synthetic resin bag characterized by being manufactured using a resin film made from a resin composition containing at least as a raw material.

6. The aforementioned resin composition, The aforementioned high-density polyethylene (HDPE) pellets make up 50 to 80 wt%, The aforementioned oyster shell component-containing pellets are 5-15 wt%, The synthetic resin bag according to claim 5, characterized in that it contains 15 to 35 wt% of the linear low-density polyethylene (metallocene LLDPE) pellets.

7. The aforementioned oyster shell component-containing pellets are The aforementioned high-density polyethylene (HDPE) in an amount of 9.7 to 29.7 wt%, The oyster shell powder is 70-90 wt%, The aforementioned zinc powder 0.3 wt%, A synthetic resin bag according to claim 6, characterized by including the following:

8. The resin composition contains titanium oxide (TiO ２ The synthetic resin bag according to claim 5, further comprising ).

9. The resin composition is barium sulfate (BaSO4). ４ The synthetic resin bag according to claim 5, further comprising ).

10. A synthetic resin bag according to any one of claims 1 to 9, characterized in that it is provided with a handle on the opening side.

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