Bamboo powder-containing film pellets and bamboo powder-containing film

Abstract

To provide a bamboo powder-containing film pellet and a bamboo powder-containing film, which, even when the average particle diameter of bamboo powder is about 50 μm, enables the reduction of the proportion of synthetic resin and also exhibits antibacterial properties.SOLUTION: A bamboo powder-containing film pellet and a bamboo powder-containing film, comprising at least 40 wt.% or less of polypropylene resin or polyethylene resin, 20 wt.% or less of bamboo powder, 50 wt.% or less of talc powder, and 3 wt.% or less of shell powder, with the average particle diameter of the bamboo powder being 50 μm or less, the talc powder having an average particle diameter of 8 μm or less, and the shell powder having an average particle diameter of 10 μm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to pellets for bamboo powder-containing films and bamboo powder-containing films containing bamboo powder.

Background Art

[0002] Bamboo has an antibacterial effect, and thus various molded articles made of synthetic resin containing bamboo powder are used. Among such molded articles, for example, there is an invention described in Patent Document 1 that uses this as a film.

[0003] Patent Document 1 discloses that by setting the average particle size of bamboo powder to 30 μm or less, a bamboo powder-containing film having antibacterial properties can be formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, from the perspective of sustainable development goals (SDGs) and the like, further reduction of the blending ratio of synthetic resin in synthetic resin films has been demanded.

[0006] Also, when using synthetic resin as a resin bag (such as a garbage bag or a plastic bag), a thin one is required.

[0007] On the other hand, as described in Patent Document 1 above, by setting the average particle size of bamboo powder to 30 μm or less, a resin sheet mixed with bamboo powder having antibacterial properties can be formed, but it has been difficult to efficiently produce a large amount of bamboo powder having an average particle size of 30 μm at low cost.

[0008] The present invention has been made in view of the above points, and an object thereof is to provide pellets for a bamboo powder-containing film and a bamboo powder-containing film that have antibacterial properties and can reduce the blending ratio of synthetic resin even when the particle size of the bamboo powder is about 50 μm.

Means for Solving the Problems

[0009] The inventor of the present application aimed to create a bamboo powder-containing film that has antibacterial properties and can reduce the blending ratio of synthetic resin by setting the types, particle sizes, and blending ratios of various materials to be blended to predetermined values even when the average particle size of the bamboo powder is about 50 μm by conducting various tests.

[0010] That is, the present invention is pellets for a bamboo powder-containing film in which at least polypropylene resin or polyethylene resin is 40% by weight or less, bamboo powder is 20% by weight or less, talc powder is 50% by weight or less, and shell powder is 3% by weight or less, and the average particle size of the bamboo powder is 50 μm or less, the average particle size of the talc powder is 8 μm or less, and the average particle size of the shell powder is 10 μm or less. According to the present invention, even when the average particle size of the bamboo powder is set to 50 μm, which is larger than 30 μm, by selecting appropriate average particle sizes and blending ratios of the bamboo powder, talc powder, and shell powder, the blending ratio of the synthetic resin can be reduced to 40% by weight or less, and pellets for a bamboo powder-containing film that can be formed into a film and have antibacterial performance can be provided.

[0011] In addition, the present invention is characterized in that, in addition to the above characteristics, the shell is a scallop shell. According to the present invention, by using a scallop shell, which has a strong antibacterial action among shells, a more effective antibacterial, bactericidal, deodorizing, and freshness-retaining action can be exhibited. It is more preferable to use a fired shell.

[0012] Furthermore, the present invention is a bamboo powder-containing film in which at least a polypropylene resin or a polyethylene resin is blended at 40% by weight or less, bamboo powder is blended at 20% by weight or less, talc powder is blended at 50% by weight or less, and shell powder is blended at 3% by weight or less, and the average particle size of the bamboo powder is 50 μm or less, the average particle size of the talc powder is 8 μm or less, and the average particle size of the shell powder is 10 μm or less. According to the present invention, even when the average particle size of the bamboo powder is set to 50 μm, which is larger than 30 μm, by selecting appropriate average particle sizes and blending ratios of the bamboo powder, talc powder, and shell powder, the blending ratio of the synthetic resin can be reduced to 40% by weight or less, and a bamboo powder-containing film with improved antibacterial performance can be provided. This bamboo powder-containing film has strong antibacterial properties due to the bamboo powder and shell powder, and can improve the freshness of food preservation. This bamboo powder-containing film can be used, for example, as a tray for storing food, a film for sealing the tray, a resin bag, or the like.

Effects of the Invention

[0013] According to the present invention, even when the average particle size of the bamboo powder is set to 50 μm, which is 30 μm or more, a bamboo powder-containing film can be formed. At the same time, it has antibacterial properties, and the blending ratio of the synthetic resin can be reduced, promoting the achievement of the SDGs.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing an example of a pellet manufacturing process of a PP resin (polypropylene resin) blended with bamboo powder. As shown in the figure, to manufacture pellets of the bamboo powder-blended PP resin, first, pellets of the PP resin, bamboo powder, talc powder, shell powder, and additive powder are prepared (Steps 1-1, 1-2, 1-3, 1-4, 1-5).

[0016] Pellet-shaped PP resin was used. Instead of the PP resin, polyethylene resin (PE resin) may be used.

[0017] As the bamboo powder, that having an average particle size of bamboo of 50 μm to 20 μm, specifically, powder having a particle size of 50 μm was used.

[0018] Talc is an inorganic mineral called talcum and is a smooth material. Its chemical name is magnesium hydrosilicate [Mg3Si4O 10 (OH)2], and this talc was finely pulverized and those having an average particle size of 8 μm or less, specifically, 5 μm were used. Talc is the softest (Mohs hardness 1) among inorganic minerals, has excellent heat resistance, and is a chemically stable substance.

[0019] As the shell powder, for example, scallop shell powder was used. Scallop shells fired at a high temperature were made into powder having an average particle size of 10 μm or less, specifically, 8 μm. Scallop shell powder has strong antibacterial properties. Although the antibacterial properties are weakened, in some cases, unfired scallop shell powder may be used. Also, other than scallop shells, other shell powders, such as oyster shell powder, may be used.

[0020] The blending ratio and the range of the average particle size of each raw material are considered to be preferably in the following ranges. Pellets of PP resin or PE resin 40% by weight or less Bamboo powder 20% by weight or less Average particle size 50 μm or less Talc powder: 50 wt% or less, average particle size: 8 μm or less Shell powder: 3 wt% or less, average particle size: 10 μm or less Additive: a small amount

[0021] And the specific mixing ratios and average particle sizes of the respective raw materials in this embodiment were as follows. PP resin pellets: 40 wt% Bamboo powder: 16 wt%, average particle size: 50 μm Talc powder: 40 wt%, average particle size: 5 μm Shell powder: 2 wt%, average particle size: 8 μm Additive: 2 wt%

[0022] Next, the bamboo powder-containing resin obtained by mixing the raw materials is put into the hopper 20 of the extrusion molding machine 10 shown in FIG. 2 and kneaded (step 2).

[0023] Next, the bamboo powder-containing resin kneaded by the hopper 20 is introduced into the cylinder 30 of the extrusion molding machine 10, heated, melted, and kneaded, and then extruded into a thin rod shape by the die 60 (step 3).

[0024] Next, the strand S, which is the extruded thin rod-shaped molded product, is cooled and solidified by the cooling means 70 (step 4).

[0025] Next, the cooled and solidified strand S is cut short by the cutter of the pelletizer 80 to obtain pellets 100 for a bamboo powder-containing film, which is a molding material (hereinafter simply referred to as "pellets") (step 5). According to this embodiment, by setting the above PP resin, bamboo powder, talc powder, and shell powder to the above respective mixing ratios and above respective average particle sizes, good pellets 100 could be obtained.

[0026] In addition, in the above extrusion molding machine 10, the pellets 100 were manufactured by installing the pelletizer 80 after manufacturing the strand S using the die 60 and the cooling means 70, but a cutting method having a structure that cuts the resin extruded from the die 60 immediately on the spot may also be used.

[0027] FIG. 3 is a schematic view showing an example of a film manufacturing apparatus. In this example, an example of a film manufacturing apparatus (inflation molding machine) 200 for manufacturing a resin bag (so-called plastic bag) using the above-mentioned pellets 100 is shown. In the figure, to manufacture a resin bag which is a kind of film, first, the pellets 100 manufactured as described above are put into a hopper 201, heated and melted in an extrusion molding machine 203, and the melted bamboo powder compounded resin is ejected from an annular opening of a circular die 205. Simultaneously with this ejection, air is ejected from the central part of the circular die 205, whereby the bamboo powder compounded resin becomes a film and swells to a predetermined size, and a long bamboo powder compounded film cylinder 207 is formed. Next, the bamboo powder compounded film cylinder 207 passes through a folding mold 209 in which both side surfaces are folded inward and the interval between the upper and lower surfaces becomes narrower toward the outlet side. Further, the bamboo powder compounded film cylinder 207 is pressed from both the upper and lower sides by a pair of pressing rollers 211, and is formed into a cylindrical film body 213 having inward folds. This film body 213 is once wound up, printed, and then the part that becomes the bottom of the bag is heat-sealed and cut according to the size of the bag, and also processed with a handle hole and an air vent hole, whereby the bamboo powder compounded resin bag is completed.

[0028] FIG. 4 is a schematic view showing another example of a film manufacturing apparatus. In this example, an example of a film manufacturing apparatus 300 for manufacturing a flat bamboo powder compounded film using the above-mentioned pellets 100 is shown. In the figure, to manufacture a bamboo powder compounded film, first, the pellets 100 manufactured as described above are put into a hopper 301, heated and melted in an extrusion molding machine 303, and the melted bamboo powder compounded film (bamboo mixed resin film) is ejected from a slit-like opening of a die (T-die) 305, and the ejected bamboo powder compounded film is wound up by a winder 309 while being cooled by a cooling means 307.

[0029] When the above-mentioned bamboo powder compounded film is used as a sealing film for covering the upper surface of a food tray containing food, for example, the growth of bacteria such as Escherichia coli and Staphylococcus aureus can be prevented by highly antibacterial bamboo powder or shell powder, and the food is less likely to spoil.

[0030] As described above, according to the present invention, even when the average particle size of bamboo powder is 50 μm, a bamboo powder-containing film can be produced. At the same time, a significant reduction in the blending ratio of synthetic resin can be achieved, promoting the achievement of SDGs, and a bamboo powder-containing film having antibacterial properties can be provided.

[0031] That is, in the present invention, even when the average particle size of bamboo powder is 50 μm, which is larger than 30 μm, by selecting appropriate average particle sizes and blending ratios of the bamboo powder, talc powder, and shell powder, the blending ratio of synthetic resin can be reduced to about 40% by weight or less, and pellets for bamboo powder-containing films and bamboo powder-containing films that can be formed into films and have improved antibacterial performance can be provided.

[0032] In the above embodiment, PP resin was used as the synthetic resin. However, even if PE resin having substantially the same properties is used, by using the same raw materials, the same blending ratio, and those having the same average particle size, it is considered that a bamboo powder-containing film that can be used as a resin bag, a sealing film, etc. can be formed.

[0033] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the technical idea described in the claims, the specification, and the drawings. Even any shape, structure, or material not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the functions and effects of the present invention are achieved. For example, in the above embodiment, an example of using a bamboo powder-containing film as a food tray, its sealing film, or a bamboo powder-containing resin bag (such as a garbage bag or a shopping bag) was described, but it can also be used for various other purposes. For example, it can also be considered to be used as a resin glove, especially a resin glove for nursing care. Also, since it has effective antibacterial properties, it can also be considered to be used as a resin film for packaging food.

[0034] In addition, the embodiments described above and shown in the respective figures can be combined with each other's description content as long as there is no contradiction in their objectives, configurations, etc. Also, the description content of the above description and each figure can be independent embodiments even if it is a part thereof, and the embodiments of the present invention are not limited to one embodiment that combines the above description and each figure.

Description of Reference Numerals

[0035] 10... Extrusion molding machine, 20... Hopper, 30... Cylinder, S... Strand, 60... Die, 70... Cooling means, 80... Pelletizer, 100... Pellets for bamboo powder compounded film, 200... Film manufacturing apparatus, 201... Hopper, 203... Extrusion molding machine, 205... Circular die, 207... Cylindrical body of bamboo powder compounded film, 209... Folding mold, 211... Pressing roller, 213... Film body, 300... Film manufacturing apparatus, 301... Hopper, 303... Extrusion molding machine, 305... Die, 307... Cooling means, 309... Take-up machine.

Claims

1. A pellet for bamboo powder blended film, in which at least a polypropylene resin or a polyethylene resin is 40% by weight or less, bamboo powder is 20% by weight or less, talc powder is 50% by weight or less, and shell powder is 3% by weight or less, and the average particle size of the bamboo powder is 50 μm or less, the average particle size of the talc powder is 8 μm or less, and the average particle size of the shell powder is 10 μm or less. The pellet for bamboo powder blended film is characterized by this.

2. The pellet for bamboo powder blended film according to Claim 1, wherein the shell is a scallop shell. The pellet for bamboo powder blended film is characterized by this.

3. A bamboo powder blended film, in which at least a polypropylene resin or a polyethylene resin is 40% by weight or less, bamboo powder is 20% by weight or less, talc powder is 50% by weight or less, and shell powder is 3% by weight or less, and the average particle size of the bamboo powder is 50 μm or less, the average particle size of the talc powder is 8 μm or less, and the average particle size of the shell powder is 10 μm or less. The bamboo powder blended film is characterized by this.

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