JPH1072544A - Biodegradable film and compost bag made thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable film which can be rapidly decomposed and utilized when exposed to a composting environment by using a composition prepared by mixing a biodegradable plastics with a dried powder of specified fibers in a specified mixing ratio. SOLUTION: This film is prepared by using a mixture prepared by mixing 98-60wt.% biodegradable plastics, desirably an aliphatic polyester (e.g. a polyester obtained by reacting a glycol with an aliphatic carboxylic acid in a 30/70 weight ratio) with 2-40wt.% powder desirably having a particle diameter of 1-80μm and obtained by drying and grinding the fibers contained in the mesocarps of coconuts. This film is formed into a bag, and this bag is used as, e.g. a compost bag for garbage. As a result, the mesocarps of coconuts, which have heretofore been discarded because of little utility, can be utilized on an industrial production scale.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable film and a compost bag obtained by using the film. The present invention relates to a composting bag which is disassembled and does not prolong the cycle required for composting.

[0002]

2. Description of the Related Art In recent years, due to increasing interest in environmental issues, measures for reducing the amount of garbage have been taken at the citizen level. For example, composting containers, so-called composters, are spreading to ordinary households with the support of local governments. Furthermore, in recent years, some household electrical appliance manufacturers have released garbage disposal machines, which are becoming more popular every year.

When garbage is processed by such a garbage processing machine, first, garbage generated in the kitchen is put into a garbage collection container (hereinafter referred to as a triangle corner) placed at a corner of a sink. . And usually in this triangle corner,
When the garbage is full, a polyethylene bag is laid for easy disposal, and the bag is removed from the triangle at the time of disposal. In order to compost the garbage thus removed with the garbage disposer, the garbage had to be removed from the polyethylene bag. Otherwise, the assimilating microorganisms in the garbage disposal machine will not easily come into contact with the garbage, which will not only increase the time required for composting, but also the bag made of synthetic resin will not be disassembled, and It had to be separated from the compost later. This work was uncomfortable for the operator, and the disposal of the used polyethylene bag was also a troublesome problem.

As a means for solving such a problem, instead of the above-mentioned polyethylene bag, a synthetic resin having biodegradability such as an aliphatic polyester such as polylactic acid or polylactone, or a modified starch-modified polyvinyl alcohol complex is used. A method of using such a bag has been proposed.

[0005] However, any of the above biodegradable synthetic resins requires at least 3 by the time of decomposition.
Since it takes more than a month, the cycle required for composting is extremely long, and a large-sized garbage disposal machine is required. Therefore, for the spread of garbage processing machines to general households, how to make the processing machine compact is a major proposition.
Compost bags that biodegrade in less than a week) have been strongly desired.

[0006] On the other hand, palm usually means coco palm, a fruit widely produced in the tropics, and has been used in various ways. That is, as shown in FIG. 2A, the embryo 2c of the fruit of the palm 2 having a thickness of 10 to 20 mm is used for palm oil, edible or medicinal materials, and is produced from the hard woody endocarp 2b having a thickness of 2 to 6 mm. Coconut shell activated carbon is a good industrial material. However, the mesocarp 2a having a thickness of 30 to 40 mm, which occupies a large part thereof, is woven from fibers (hereinafter, referred to as coconut fibers) to a rope and a string, and is not used for any other purpose.

[0007] This coconut fiber 3 is shown in FIG.
As shown in the enlarged view of FIG.
It has a thick film fiber structure of about 0.7mm in length and about 20μm in width with pores of the cell membrane penetrating through b. It is light, stiff and elastic, and has poor heat resistance and is durable to air and water. (Handbook of Inorganic Organic Industrial Materials, edited by Shoichiro Nagai, p.
788. Others (first edition on March 20, 1960, published by Toyo Keizai Shimpo). Furthermore, when these are compressed by pressurizing with a press or the like, they have a property that the volume expands 5 to 6 times when water is added. This phenomenon is presumed to be caused by memorizing the shape of the compressed dry fiber when it was in its natural state and restoring it to the state of retaining the luminal membrane at the cell level.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such a situation, and when exposed to a composting environment, the biodegradation proceeds rapidly so that the biodegradation can be assimilated. It is an object of the present invention to provide a film and a composting bag using the film, and to utilize the mesocarp of coconut, which has been conventionally used little and is wasted, at an industrial production level.

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that by blending a predetermined amount of dry powder of fiber contained in the mesocarp of a palm with a biodegradable resin, the biodegradable resin is produced. The inventors have found that the decomposition rate is significantly improved, and have reached the present invention. That is, according to the present invention, a biodegradable film is characterized in that 98 to 60% by weight of a biodegradable plastic is mixed with 2 to 40% by weight of a dry powder of a fiber contained in a mesocarp of a palm. Is provided, and more preferably, a biodegradable film is provided, wherein the biodegradable plastic is an aliphatic polyester, and further, the biodegradable film according to any of the above is formed into a bag shape. A compost bag characterized by being formed is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail. Examples of the biodegradable plastic used in the production of the biodegradable film of the present invention include polylactic acid, polyhydroxyalkanoate, lactone resin, and aliphatic such as polyester obtained from low-molecular-weight aliphatic dicarboxylic acid and low-molecular-weight aliphatic diol. Polyester resin; modified starch-modified polyvinyl alcohol complex; and the like can be used,
Aliphatic polyesters are particularly preferably used from the viewpoint of moldability and biodegradability.

Next, the coconut fiber dry powder (hereinafter referred to as coconut powder) used in the present invention will be described. FIG. 1A is a block diagram showing a raw material composition of the biodegradable film of the present invention, and FIG. 1B is a block diagram showing an example of a method for producing the raw material. That is, in order to obtain coconut powder, the mesocarp 2a of coconut palm 2 (hereinafter referred to as coconut shell) is exposed to fresh water for 12 to 16 months to dissolve the flesh, and only the fiber is collected. The water content is reduced to 10% by performing forced drying with hot air for about 8 hours to remove the salt and tannin contained therein by exposure, and then subjected to a compression treatment by pressurizing with a press machine or the like. Next, it is pulverized using a pulverizer such as a ball mill, a hammer mill, and a jet mill to obtain powder. Although the size of the coconut powder is not particularly limited, it is desirable to set the particle size in the range of 1 to 80 μm in view of the appearance when formed into a film, the energy cost required for pulverization, and the like.

The mixing ratio of the biodegradable plastic and the coconut powder is set to a weight ratio of biodegradable plastic / coconut powder = 98/2 to 60/40. If the compounding ratio of the biodegradable plastic exceeds this range, the improvement of the biodegradation rate is not remarkable and it is not preferable. Exceeding this will not only cause difficulty in film forming, but also make the resulting film brittle, which is not preferable.

In the present invention, the addition of known antioxidants, carbon black, coloring agents such as various pigments, inorganic fillers, lubricants, antiblocking agents, surfactants and the like does not hinder this. Further, in order to improve the dispersibility of the coconut powder in the biodegradable plastic, the coconut powder may be subjected to a surface treatment with a silane-based coupling agent.

Next, a specific method for producing the biodegradable film of the present invention will be described. Coconut powder is usually
It is melt-kneaded into biodegradable plastic and pelletized.
For this operation, a well-known kneading device such as a Banbury mixer, a Henschel mixer, a single-screw kneader, a multi-screw kneader, a mixing roll, or a kneader is suitably used. Next, a film is formed using the obtained pellets. In forming the film, a known inflation method or T-die method film forming machine can be used. Further, a stretching step may be added simultaneously with or after the film formation. The thickness of the biodegradable film is appropriately set according to the strength required for the intended use and the decomposition rate,
Usually 1 for industrial use, seeding bags for soil greening, etc.
100-2000 μm, 10-500 μm for composting bags, garbage bags, shopping bags, and various packaging film applications
Generally, it is set between m. It is also possible to laminate or coat a biodegradable resin layer in which coconut powder is not blended on the surface of the biodegradable film of the present invention, and furthermore, the biodegradability of the biodegradable film of the present invention. On the surface of the biodegradable film within a range that does not significantly inhibit
A synthetic resin such as a polyurethane resin may be laminated or coated.

Using the biodegradable film thus obtained, a compost bag is manufactured. Here, as a method of producing a compost bag, the biodegradable film of the present invention may be sealed two- or three-way, or, if the film is tubular, sealed at the bottom by a known bag-making method. It is common to shape it into a shape. In addition, holes may be formed in the bottom or the entirety of the bag for the purpose of improving the drainage of the composting bag.

The biodegradable film of the present invention produced by the above method and a composting bag using the same are as follows:
When this is left in a composting environment, its biodegradability is lower than that produced by biodegradable plastic alone.
Dramatically improved. This is because the coconut powder blended is a natural organic material, so many microorganisms prefer it, especially before the plastic component, which first decomposes the coconut powder component and breaks down the overall shape, which is the other component of the plastic component. It seems to be the result of creating a situation where the activity of microorganisms is also activated. In addition, coconut powder swells to about 5 to 6 times its volume when exposed to moisture. Therefore, the biodegradable film of the present invention in which the coconut powder is blended, in a composting environment,
Swelling of the coconut powder causes countless cracks. This results in a significant increase in the surface area of the film. This is considered to be one of the reasons why the biodegradability of the biodegradable film of the present invention is remarkably improved.
In addition, the biodegradable raw film of the present invention is suitable as such a composting bag, but is also widely used as a seeding bag for soil greening, a garbage bag, a shopping bag, and further various packaging and industrial films. It can be used for

[0017]

The present invention will be described in more detail with reference to the following examples.

[Production Example] Palm mesocarp was taken out from a coconut shell, and was placed in fresh water for one year to dissolve and remove meat. Next, it was exposed to the sun for 3 years to remove salt and tannin contained therein, and further subjected to forced drying with hot air of 105 ° C. for 8 hours to reduce the water content to 10%. And compression processing was performed using the press machine. The thus obtained compression-treated product was pulverized by a jet mill and then classified by a sieve to obtain a coconut powder having a mesh passing of 400 mesh.
Observation of the obtained coconut powder with a scanning electron microscope confirmed that the average particle size was about 20 μm.

Examples 1-4 A biodegradable aliphatic polyester obtained by synthesizing a glycol and an aliphatic carboxylic acid at a weight ratio of 30:70 ("Bionore" manufactured by Showa Polymer Co., Ltd.) ), 5% by weight (Example 1), 10% by weight (Example 2), 20% by weight (Example 3), and 40 parts by weight (Example 4) of the coconut powder obtained in the above Production Example were blended. The mixture was melt-mixed and granulated to obtain a raw material for producing a biodegradable film. Next, a film was formed at a processing temperature of 160 ° C. by using a φ40 inflation extruder, and a thickness of 30
A tube having a size of μm and a folding width of 300 mm was obtained. This tube was sealed at the bottom to obtain a compost bag of 300 × 400 mm. These compost bags were evaluated for tensile strength and elongation in accordance with JIS K 1701.
Table 1 shows the results. Also, put the garbage in these compost bags, put it in a commercial garbage disposal machine,
The state of the biodegradation was visually observed. Table 2 shows the results.

[Comparative Example 1] A biodegradable aliphatic polyester (manufactured by Showa Polymer Co., Ltd., trade name: “Bionole”) obtained by synthesizing glycol and aliphatic carboxylic acid at a weight ratio of 30:70 was used. A film was formed at a processing temperature of 160 ° C. using a φ40 inflation extruder to obtain a tube having a thickness of 30 μm and a folding width of 300 mm. This tube was sealed at the bottom to obtain a compost bag of 300 × 400 mm. This compost bag was evaluated for tensile strength and elongation according to JIS K 1701. Table 1 shows the results. In addition, garbage was put into the compost bag, put into a commercial garbage disposal machine, and the state of biodegradation was visually observed. Table 2 shows the results.

Comparative Example 2 A compost bag was obtained in exactly the same manner as in Examples 1 to 4, except that the amount of coconut powder was changed to 50% by weight. This compost bag was evaluated for tensile strength and elongation according to JIS K 1701. Table 1 shows the results. In addition, garbage was put into the compost bag, put into a commercial garbage disposal machine, and the state of biodegradation was visually observed. Table 2 shows the results.

[0022]

[Table 1]

According to Table 1, the amount of coconut powder was 4%.
When the content exceeds 0% by weight, the mechanical strength of the composting bag decreases, and it is found that there is a practical problem.

[0024]

[Table 2]

From Table 2, it is clear that the blending of coconut powder significantly improves the biodegradation rate.

[0026]

As described above, according to the present invention, a biodegradable film in which a biodegradable plastic is compounded with coconut powder and having an improved biodegradation rate, and the biodegradable film are used. A composting bag is provided. These are very useful in disseminating composting, which has been attracting attention as one of the major means of reducing garbage, while interest in environmental issues is rising. Further, the present invention provides a use for utilizing the mesocarp of coconut which has been conventionally discarded for a small amount and wastefully at an industrial production level.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a biodegradable film of the present invention, a raw material of a composting bag using the biodegradable film, and a configuration of a manufacturing method thereof.

FIG. 2 illustrates a coconut shell used in the present invention.
(A) is a sectional view of coconut palm, (B) is an enlarged sectional view of coconut fiber.

[Explanation of symbols]

1. 1. Biodegradable plastic Palm 2a. Mesocarp 2b. Endocarp 2c. Embryo 3. Coconut shell fiber 3a. Lumen 3b. 3. Sawtooth projection 4. Mixture (pellet) of coconut shell fiber powder and biodegradable plastic Coconut powder

Claims (3)

[Claims] 1. Biodegradable plastic 98 to 60% by weight
In addition, dry powder of fiber contained in the mesocarp of palm is
A biodegradable film characterized by comprising 0% by weight. 2. The biodegradable film according to claim 1, wherein the biodegradable plastic is an aliphatic polyester. 3. A composting bag, wherein the biodegradable film according to claim 1 is formed into a bag.