JP2007068458A - Mulch sheet for agricultural use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mulch sheet for agricultural use, resistant to the lowering of strength in wet state, resistant to breakage, inhibiting the growth of weeds, preventing the lowering of soil temperature at night, dispensing with the recovery work after use and giving no adverse effect on the ecological system after biodegradation of the sheet. <P>SOLUTION: The mulch sheet for agricultural use is composed of a resin composition containing powdery activated carbon dispersed in a biodegradable resin. Preferably, the powdery activated carbon has an average particle diameter of 0.1-100 μm and the amount of the activated carbon is 0.1-20 mass% based on the biodegradable resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an agricultural multi-sheet, and more particularly to an agricultural multi-sheet having high safety and health even after use.

  Control of weeds in arable land is to control weeds competing with crops in paddy fields and fields and to preserve cultivated land. Since ancient times, it has been said that rice farming and field farming are fights against weeds, and human beings have invested a great deal of effort to control weeds in cultivated land as well as the expansion of arable land. Herbicides that protect crops and selectively control weeds have been developed and are widely used. However, in recent years, as the tendency of consumers to focus on nature and safety has increased, crop-free pesticides have been developed. The demand for cultivation has increased, and a method not using a herbicide has been tried to control weeds in arable land. For example, a method of releasing Aigamo, horseshoe shrimp, carp and the like in paddy fields is performed.

  In addition, attempts have been made to make pesticide-free rice by a method of actively generating algae in paddy fields. However, the release of animals requires a great deal of labor for management, and the generation of water algae can cause harm to rice, and water algae do not necessarily dominate in competition with weeds.

  Conventionally, a plastic film multi-sheet (hereinafter referred to as “plastic multi”) has been used as a method that does not have such a problem, and a black and light-shielding carbon black compound prevents the generation and growth of weeds. Known as black multi. However, since the conventional plastic mulch is made of non-biodegradable plastic, it was necessary to collect the mulch at the time of crop harvesting.

  For this reason, a paper mulch has been proposed as a mulch taking advantage of the properties of paper that corrodes and decomposes in the soil. For example, Patent Document 1 discloses a chitosan main material containing, as a main component, a light shielding agent comprising carbon black and a water-insoluble binder and chitosan or a derivative thereof on a support made of paper made from wood pulp. Agricultural multi-sheet provided with a material layer is described, Patent Document 2 has a specific elongation at break, consists of two layers of a light reflecting layer and a colored pulp layer, and contains carbon black in the colored pulp layer A paper multi-sheet is described.

However, the paper mulch generally has a reduced strength when it gets wet with water, is expensive, and has a poor laying workability and may be easily broken. Moreover, since carbon black contained in black mulches contains harmful substances such as benzpyrene having carcinogenicity, there is a concern about the influence on ecosystems after biodegradation of mulch.
JP-A-6-62680 JP 2000-342082 A

  Therefore, the present invention does not show a decrease in strength due to water wetting, is difficult to break, inhibits the growth of weeds, and at the same time prevents a decrease in nighttime land temperature, does not require recovery after use, and is an ecosystem after biodegradation The purpose is to provide an agricultural multi-seat that does not adversely affect the environment.

  As a result of earnest research to solve the above problems, the present inventors can prevent sunlight from being transmitted to the ground surface by laying a film made of a resin composition in which powdered activated carbon is dispersed in a biodegradable resin on the cultivated land surface. It has been found that it can inhibit the growth of weeds and raises the ground temperature, and at the same time, the biodegradable resin and activated carbon do not contain harmful substances, so it has extremely high safety and health even after the use of the multi-sheet. Reached.

  That is, the present invention provides an agricultural multi-sheet comprising a resin composition in which powdered activated carbon is dispersed in a biodegradable resin.

  In the present invention, the powdered activated carbon preferably has an average particle size of 0.1 to 100 μm, and the resin composition preferably contains starch or a derivative thereof.

  According to the present invention, activated carbon blocks light rays and inhibits the growth of weeds, prevents a decrease in nighttime temperature, and is made of a biodegradable resin, so there is no need for recovery after use, and even after biodegradation. An agricultural multi-seat with high safety and health that does not adversely affect the ecosystem can be provided. Moreover, since it is a sheet | seat which consists of a biodegradable resin composition, the workability | operativity is also favorable, without the fall of the intensity | strength by water-wetting and being easy to tear like paper multi.

  In the present invention, as the biodegradable resin, any conventionally known biodegradable resin can be used and is not particularly limited. For example, a biodegradable resin having an ester group in its structure and further having thermoplasticity is included, such as polyhydroxycarboxylic acids, polylactones, aliphatic polyesters, aliphatic aromatic polyesters, polyester-carbonates. Can be mentioned.

  The polyhydroxycarboxylic acid is preferably a polymer of hydroxycarboxylic acid having about 2 to 9 carbon atoms, specifically, polylactic acid, polyhydroxybutyric acid, a copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid. As the polylactones, ring-opening polymers of lactones having about 4 to 6 carbon atoms are preferred, and specific examples include polybutyrolactone and polycaprolactone. The aliphatic polyester is preferably a polyester from an alkylene glycol having about 2 to 4 carbon atoms and an aliphatic dicarboxylic acid having about 2 to 9 carbon atoms, such as polybutylene succinate, polybutylene succinate-adipate, etc. Is mentioned.

  Examples of the aliphatic aromatic polyesters include copolymerized polyesters of alkylene glycol having about 2 to 4 carbon atoms, aliphatic dicarboxylic acid having about 2 to 9 carbon atoms, and aromatic dicarboxylic acid having about 8 to 10 carbon atoms. Examples thereof include polybutylene succinate-terephthalate, polybutylene adipate-terephthalate, and polytetramethylene adipate-terephthalate. Examples of polyester carbonates include alkylene glycol and carbon having about 2 to 4 carbon atoms. A polyester-carbonate of an aliphatic dicarboxylic acid having 2 to 9 carbon atoms and carbon dioxide gas is preferable, and examples thereof include polybutene succinate-carbonate.

  In addition to the above, examples of the biodegradable resin include cellulose, cellulose acetate, chitin, chitosan, collagen, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and modified starch. Two or more biodegradable resins may be mixed and used.

  As the powdered activated carbon, activated carbon having an average particle diameter of 0.1 to 100 μm is preferable from the viewpoint of coloring power and hiding power (shielding power). If the average particle size is less than 0.1 μm, it is difficult to produce by mechanical pulverization. On the other hand, if the average particle size exceeds 100 μm, the coloring power and hiding power decrease, which is not preferable. A more preferable average particle diameter is 1 to 50 μm.

  There is no particular limitation on the raw material of the above-mentioned powdered activated carbon, the production method, sawdust, coconut shell, coal etc. as raw materials, activated carbon activated by chemicals or steam can be used, in addition to activated carbon commercially available as powdered coal, Granular charcoal can be crushed and used. Activated carbon has a long history of use in the food and beverage industry, such as water treatment in waterworks, purification of beer, liquor, soy sauce, etc. in breweries, purification of pharmaceuticals, and decolorization of refined sugar. It does not release harmful substances even after biodegradation, does not adversely affect the ecosystem, and has high safety and health. Activated carbon inhibits the growth of weeds by absorbing ultraviolet and visible light. At the same time, activated carbon can absorb near-infrared rays and prevent a decrease in the land temperature at night.

  In this invention, it is desirable to add 0.1-20 mass% of powdered activated carbon with respect to biodegradable resin. If the amount of powdered activated carbon is less than 0.1% by mass, concealment and temperature rise are insufficient, while if it exceeds 20% by mass, the resulting agricultural multi-sheet tends to be brittle. A more preferable amount of powdered activated carbon is 0.5 to 5% by mass.

  It is preferable to add a powdered activated carbon dispersant to the resin composition in the present invention. Examples of the dispersant include biodegradability derived from natural products such as hydrogenated castor oil, starch and derivatives thereof, and fatty acid metal salts. The dispersing agent which has can be mentioned. Among these, starch and derivatives thereof can be preferably used from the viewpoint of biodegradability. Examples of the starch derivative include soluble starch, dextrin, British gum, oxidized starch, and esterified starch that are used as a pharmaceutical excipient or food additive. Although the addition amount of these dispersing agents is not specifically limited, It is desirable to add 0.1-20 mass%. More preferably, it is about 0.5-5 mass%.

  The resin composition in the present invention is a usual method, for example, using a twin-screw extruder or the like, knead the biodegradable resin in a heat-melted state, powdered activated carbon, a dispersant and the like, and granulate to obtain pellets, This pellet is remelted by, for example, an inflation method or a T-die method and formed into a film or a sheet to produce an agricultural multi-sheet. The agricultural multi-sheet of the present invention can be widely used for paddy field / field action multi-film, fruit tree reinforcement, planting pot, road median and side weeding sheet, slope weeding sheet for civil engineering work, etc. .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In addition, in an Example, a part is a mass part.

[Example 1]
Biodegradable resin: 100 parts of Bionore 3001 (produced by Showa Polymer Co., Ltd.), powdered activated carbon: Dazai K (average particle diameter after dispersion: 0.7 μm, produced by Nimura Chemical Co., Ltd.) and dispersant 2 parts of soluble starch was added, blended with a tumbler to obtain a resin composition, and kneaded at a resin composition temperature of 200 ° C. in a 25 mm same-direction twin screw extruder to granulate pellets. Using this pellet, a 100 μm agricultural multi-sheet was prepared with a 25 mm inflation extruder. The obtained agricultural multi-sheet was spread on a paddy field, and the soil temperature was measured every 4 hours. The results are shown in Table 1.

[Example 2]
An agricultural multi-sheet was prepared in the same manner as in Example 1 except that 60 parts of Lacia H100 (Mitsui Chemicals) and 40 parts of Ecoflex FBX7011 (BASF) were used as biodegradable resins. In the same way as in No. 1, it was laid on a paddy field and the ground temperature was measured. The results are also shown in Table 1.

[Example 3]
Agricultural multi-sheets were prepared in the same manner as in Example 2 except that 8 parts of powdered activated carbon and 3.2 parts of soluble starch were used. The results are also shown in Table 1.

[Comparative Example 1]
In Example 1, an agricultural multi-sheet was prepared without adding powdered activated carbon and a dispersant. In the same manner as in Example 1, it was laid on a paddy field and the ground temperature was measured. The results are shown in Table 1.

  As shown in Table 1, it was confirmed that the agricultural multi-sheet of the present invention to which powdered activated carbon was added was excellent in the rise of the earth temperature and prevented the nighttime earth temperature from being lowered.

According to the present invention, activated carbon blocks light rays and inhibits the growth of weeds, prevents a decrease in nighttime temperature, and is made of a biodegradable resin, so there is no need for recovery after use, and even after biodegradation. An agricultural multi-seat with high safety and health that does not adversely affect the ecosystem can be provided. Moreover, since it is a sheet | seat which consists of a biodegradable resin composition, the workability | operativity is also favorable, without the fall of the intensity | strength by water wetting and being easy to tear like paper mulch.

Claims (3)

  An agricultural multi-sheet comprising a resin composition in which powdered activated carbon is dispersed in a biodegradable resin.   The agricultural multi-sheet according to claim 1, wherein the powdered activated carbon has an average particle size of 0.1 to 100 µm. The agricultural multi-sheet according to claim 1, wherein the resin composition contains starch or a derivative thereof.