JP2002348406A - Disposition method os agricultural mulching film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reclaiming disposition method to dispose an agricultural mulching film made from biodegradable resin which remains lying in soil, with little fluctuation in biodegradability depending upon climate, nature of the soil in an area where it is disposed and seasons by promoting biodegradation to enable short-term degradation, after duration of use. SOLUTION: In the landfill disposition method of the agricultural mulching film made from biodegradable resin, a compound or/and a microorganism capable of degrading the biodegradable resin composing the film is brought into contact with the surface of the mulching film lying, the film is landfilled by putting in soil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for disposing of an agricultural mulching film made of a biodegradable resin by landfilling. And landfill disposal method that can be decomposed in a short period of time.

[0002]

2. Description of the Related Art In recent years, in response to the problem of environmental degradation due to environmental accumulation due to landfill disposal after the end of the use period of a synthetic resin molded article, a biodegradable resin biodegradable by microorganisms and enzymes in soil has been developed. The use has attracted attention, especially agricultural films and sheets used in a state close to the soil, for example, used to cover the ridges and the like for the purpose of preventing elevation of soil temperature and evaporation of water, suppression of weeds, etc. In the mulching film, for example, in Japanese Patent Publication No. 59-8365, a biodegradable mulching film obtained by molding a mixture of polycaprolactone and an aliphatic polyamide into an ester-amide exchange product obtained by heating and melting, JP-A-8-2
No. 59,823 discloses a biodegradable mulching film comprising a polymer containing a lactic acid unit.
No. 360, there is disclosed a biodegradable mulching film in which each unit of an aliphatic oxycarboxylic acid and an aliphatic or alicyclic diol and an aliphatic dicarboxylic acid is composed of an aliphatic polyester copolymer in a specific ratio. -295929
In Japanese Patent Laid-Open Publication No. H11-163, a biodegradable mulching film or the like comprising a two-layer laminate composed of two kinds of mixtures having different mixing ratios of polylactic acid and an aliphatic polyester containing a urethane bond is proposed.

However, the conventionally known polylactic acid, aliphatic polyester, and the like have insufficient biodegradation rates, and have not yet reached practical use. As a method of improving from
JP-A-39381 and JP-A-8-92419 disclose a method of blending starch or a modified starch with polylactic acid, aliphatic polyester resin or the like, and JP-A-10-1019.
Japanese Patent Application Laid-Open No. 19-31632 discloses a method of blending a nucleating agent with a biodegradable resin such as polycaprolactone.
No. 71 discloses a method of copolymerizing lactic acid and an aliphatic hydroxycarboxylic acid, and JP-A-9-87499 discloses a method of mixing a lactic acid-based polymer and a hydroxyalkanoic acid-based polymer. JP-A-10-53698 discloses a method of mixing polylactic acid and poly (3-hydroxybutyric acid). JP-A-2000-129105 discloses an aliphatic polyester and poly (3-hydroxybutyric acid). (Japanese Patent Application Laid-Open No. 9-3150) proposes a method of adding a polyvalent isocyanate compound to a mixture of polylactic acid and an aliphatic polyester to cause a reaction.

As a method for improving the biodegradation rate from the aspect of a degrading enzyme and the like, for example, JP-A-6-319532
JP-A-6-319533 discloses a method for decomposing polycaprolactone or 3-hydroxybutyric acid-3-hydroxyvaleric acid copolymer using a specific microorganism or enzyme. The publication discloses a method of decomposing by using an anaerobic bacterium.
No. 7,768, JP-A-11-2257 discloses a method for decomposing an aliphatic polyester using a specific microorganism.
No. 55 proposes a method of decomposing polybutylene succinate using a specific enzyme, and the like.

However, the method of improving the biodegradation rate of the biodegradable resin from the viewpoint of the resin and the method of improving the biodegradable enzyme from the viewpoint of the degrading enzyme and the like can also improve the moldability and the mechanical strength as a molded article. As the retained biodegradable resin, the biodegradation rate itself is still not sufficient, and the climate climate and soil quality of the landfill disposal area
There are also problems such as the difference in biodegradation rate depending on the season and the like, and it is presently required to solve these points early.

[0006] Therefore, as an agricultural multi-film made of a biodegradable resin, in the disposal treatment after the end of the use period, the laid mulching film can be landfilled by plowing it into the soil and biodegraded early. If possible, it can save a lot of labor such as film collection, which leads to great labor saving, but at present, from the above-mentioned problem,
At present, it has not been possible to plow it into the soil and dispose of it in the laid state.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and promotes biodegradation after a period of use of an agricultural mulching film made of a biodegradable resin. Landfill disposal, which reduces the biodegradability due to the climate, soil quality, season, etc. of the area to be landfilled, and allows for disposal by plowing into the soil as it is laid. It aims to provide a method.

[0008]

SUMMARY OF THE INVENTION According to the present invention, in disposing of agricultural mulching film made of biodegradable resin by landfill, the resolution of the biodegradable resin constituting the film is placed on the surface of the mulching film in the laid state. And a method of disposing of a mulching film for agricultural use, in which the film is landed by plowing the film into soil after contacting with a compound or / and a microorganism having the same.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for disposing of a mulching film for agricultural use of the present invention, the biodegradable resin constituting the mulching film is not particularly limited. Molding processability, and a resin having mechanical strength as a molded body, etc.
For example, polycondensates and copolycondensates of aliphatic or alicyclic diols and aliphatic or alicyclic dicarboxylic acids, polycondensates and copolycondensates of hydroxycarboxylic acids, polycondensates and copolycondensates of lactones Examples include condensates, and copolycondensates of these diols and dicarboxylic acids, and lactones and hydroxycarboxylic acids.

Here, examples of the aliphatic or alicyclic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,2-
Cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethylol, 1,4-cyclohexanediol
Cyclohexane dimethylol and the like, as the aliphatic or alicyclic dicarboxylic acid, for example, oxalic acid, malonic acid,
Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and these dicarboxylic acids And derivatives thereof such as an alkyl ester having about 1 to 4 carbon atoms and an anhydride.

Further, the hydroxycarboxylic acid includes
For example, glycolic acid, lactic acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3-methyl-n-butyric acid, 2-hydroxy-3,3-dimethyl-n-butyric acid, 3-hydroxy-n-butyric acid, -Hydroxy-n-butyric acid, 2-hydroxy-n-valeric acid, 3-hydroxy-n-valeric acid, 4-hydroxy-n-valeric acid, 5-hydroxy-n-valeric acid,
2-hydroxy-n-hexanoic acid, 2-hydroxy-i
-Hexanoic acid, 3-hydroxy-n-hexanoic acid, 4-
Hydroxy-n-hexanoic acid, 5-hydroxy-n-hexanoic acid, 6-hydroxy-n-hexanoic acid and the like,
Examples of the lactone include propiolactone, butyrolactone, valerolactone, caprolactone, laurolactone, and the like.

[0012] Among these biodegradable resins, in the present invention, aliphatic or alicyclic diols, aliphatic or alicyclic dicarboxylic acids, and aliphatic or alicyclic oxycarboxylic acids Alternatively, an alicyclic polyester resin is preferred.

[0013] The aliphatic or alicyclic polyester resin may be derived from an aliphatic or alicyclic diol in terms of moldability, mechanical strength as a molded article, and biodegradability. 35 to 49.99 mol% of units, 35 to 49.99 mol% of constituent units derived from an aliphatic or alicyclic dicarboxylic acid, and 0. 4 mol% of constituent units derived from an aliphatic or alicyclic oxycarboxylic acid. 02-30
Mol% is preferable, and the structural unit derived from an aliphatic or alicyclic diol is 40 to 49.75 mol%,
The constituent unit derived from an aliphatic or alicyclic dicarboxylic acid is 40 to 49.75 mol%, and the constituent unit derived from an aliphatic or alicyclic oxycarboxylic acid is 0.5 to 20 mol%.
And more preferably 45 to 49.5 mol% of structural units derived from an aliphatic or alicyclic diol, and 45 structural units derived from an aliphatic or alicyclic dicarboxylic acid.
It is particularly preferable that the amount of the structural unit derived from an aliphatic or alicyclic oxycarboxylic acid is 1 to 10 mol%.

The structural unit derived from an aliphatic or alicyclic diol is a unit derived from an aliphatic diol having 2 to 10 carbon atoms or a unit derived from an alicyclic diol having 3 to 10 carbon atoms. A structural unit derived from an aliphatic or alicyclic dicarboxylic acid is a unit derived from an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, or a unit derived from an alicyclic dicarboxylic acid having 3 to 12 carbon atoms. Is preferred, and
It is preferable that the constituent unit derived from the aliphatic or alicyclic oxycarboxylic acid is a unit derived from a 2-hydroxyalkanoic acid having 2 to 12 carbon atoms. In addition, these aliphatic or alicyclic diols, aliphatic or alicyclic dicarboxylic acids, and aliphatic or alicyclic oxycarboxylic acids include those exemplified above.

Among these, the structural unit derived from an aliphatic or alicyclic diol is a unit derived from 1,4-butanediol, and the structural unit derived from an aliphatic or alicyclic dicarboxylic acid is succinic acid. An aliphatic polyester resin, which is a unit derived from an aliphatic or alicyclic oxycarboxylic acid, is a unit derived from lactic acid or glycolic acid.

The aliphatic or alicyclic polyester resin may be, for example, an aromatic diol such as 2,2-bis (4'-hydroxyphenyl) propane or an aromatic diol such as terephthalic acid or isophthalic acid. Aromatic dicarboxylic acids, and aromatic oxycarboxylic acids such as hydroxybenzoic acid, and trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, gallic acid, and apple acid, tricarballylic acid, trimellitic acid, trimesic acid , A trifunctional or higher polyfunctional component such as pyromellitic acid may be contained as a constituent unit in an amount of 5 mol% or less based on all components, and the aliphatic or alicyclic polyester resin is, for example, JP-A-8-23
It is manufactured by a known method described in, for example, Japanese Patent No. 9461.

The molecular weight of the biodegradable resin in the present invention is from 10,000 to 200,000 in terms of the number average molecular weight from the viewpoints of film moldability, mechanical strength as a film, and biodegradability. Preferably it is.

Further, the biodegradable resin in the present invention comprises:
Antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, lubricants, antiblocking agents, mold release agents, antifogging agents, nucleating agents, plasticizers, coloring agents, fillers, etc. commonly used in resin moldings are included. It may be contained.

The mulching film for agricultural use in the present invention can be obtained by a conventionally known film forming method such as extrusion molding of the biodegradable resin from an extruder equipped with a T-die or an annular die, or calendering with a calender roll. Formed by

The thickness of the agricultural mulching film of the present invention is not particularly limited.
It is about 10 to 100 μm, and preferably about 20 to 50 μm.

In the method for disposing of a mulching film for agricultural use of the present invention, the compound having the resolution of the biodegradable resin constituting the film may be formed on the surface of the mulching film for agricultural use in a laid state composed of the biodegradable resin. After contacting the microorganisms and microorganisms, the film is landed by plowing the film into soil.

The compound or microorganism having the ability to degrade the biodegradable resin may be any compound having the ability to decompose the biodegradable resin to be discarded. Examples of the compound include quick lime, slaked lime, and the like. Calcium carbonate fertilizers, calcareous fertilizers such as shell fossil fertilizers, and various enzymes such as lipases, esterases, proteases and other hydrolases, oxidases such as peroxidase, monooxygenase and dioxygenase, and the like. For example, Pseudomonas (Pseudomonas
s) Genus, Bacteroides
Genus, Mucor, Humicola
ola) genus, Thermomyces
Genus, Talaromyces, Chaetomium, Torula
la) genus, Sporotrichum
m) Genus, Malbranchea
And the genus Acidovorax. Among these, in the present invention,
Various enzymes such as hydrolases and oxidative enzymes are preferred.

In order to bring these compounds and microorganisms into contact with the mulching film surface in the laid state, there is no particular limitation. It is preferable to apply, spray, spray, or the like on the film surface as a liquefied substance such as a water dispersion or an aqueous dispersion. These can be encapsulated or microencapsulated before use. In addition, at the time of the contact, it is preferable to add a surfactant or a water-absorbing material to the liquefied material in order to ensure the contact of the compound and microorganisms on the film surface or to retain moisture on the film surface. .

It is preferable that the compound or microorganism is brought into contact with the surface of the film for at least 3 hours to reduce the material strength of the film and then plowed. The film can be easily broken into pieces and can be easily plowed, and the biodegradation after plowing can be further promoted.

In the present invention, plowing refers to mixing into the soil by the power of a cultivator or the like and human power such as a plow or hoe.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Consisting of 47.8 mol% of a constitutional unit derived from 1,4-butanediol, 47.8 mol% of a constitutional unit derived from succinic acid, and 4.4 mol% of a constitutional unit derived from lactic acid. An aliphatic polyester resin having a number average molecular weight of 69000 is formed into an inflation film by an extruder equipped with an annular die, and a tube is cut to have a thickness of 5 mm.
An agricultural multi-film having a thickness of 0 μm, a width of 1 m and a length of 100 m was formed. The tensile rupture strength of the obtained film is 350
kg / cm ² and tensile elongation at break were 380%.

This film was laid on a ridge in a test field at the Yokohama Science and Technology Center of Mitsubishi Chemical Corporation, with both left and right ends of the film buried in the soil and a central part exposed on the ground. After a lapse of months, when the film was visually observed for damage, no significant damage was observed at both ends and the center. Subsequently, lipase (Rhizopus del) was applied to the surface of the center of the film and the soil surface at both ends.
emer, manufactured by SIGMA) 5 units / ml and surfactant (“Plysurf A210G” manufactured by Daiichi Kogyo Seiyaku)
20 ml / m 2 of phosphate buffer containing 0.005% by weight
After spraying at a rate of ² and leaving it for 24 hours a day, after confirming that the material strength of the film had decreased, it was landfilled by plowing using a cultivator. The plowing of the film could be easily performed, and after two months, the furrow soil was collected. However, the film test piece was completely biodegraded, and no remaining residue was confirmed.

Comparative Example 1 A landfill test was performed in the same manner as in Example 1 except that the phosphate buffer was not sprayed using the same film as used in Example 1. In addition, the film wrapped around the cultivator, and the film could not be plowed.

Example 2 From 48.8 mol% of a structural unit derived from 1,4-butanediol, 48.8 mol% of a structural unit derived from succinic acid, and 2.4 mol% of a structural unit derived from glycolic acid A landfill test was conducted in the same manner as in Example 1 except that an aliphatic polyester resin having a number average molecular weight of 42,500 was used. Plowing of the film can be done easily,
Two months later, the furrow soil was collected, but the film test piece was completely biodegraded, and no residual was confirmed.

Comparative Example 2 A landfill test was performed in the same manner as in Example 2 except that the phosphate buffer was not sprayed using the same film as used in Example 2. In addition, the film wrapped around the cultivator, and the film could not be plowed.

Example 3 A landfill test was carried out in the same manner as in Example 1 except that a commercially available aliphatic polyester resin ("Bionore" manufactured by Showa Polymer Co., Ltd.) was used. The plowing of the film could be easily performed, and after two months, the furrow soil was collected, but the film test piece was biodegraded, and almost no residual was observed.

Comparative Example 3 A landfill test was performed in the same manner as in Example 3 except that the phosphate buffer was not sprayed, using the same film as used in Example 3, and when plowing was performed using a tilling machine. In addition, the film wrapped around the cultivator, and the film could not be plowed.

Example 4 A landfill test was conducted in the same manner as in Example 1 except that a commercially available polylactic acid resin ("Nature Works" manufactured by Cargill Dow Japan KK) was used. The plowing of the film could be easily performed, and after two months, the furrow soil was collected, but the film test piece was biodegraded, and almost no residual was observed.

Comparative Example 4 A landfill test was conducted in the same manner as in Example 4 except that the phosphate buffer was not sprayed using the same film as that used in Example 4, and when plowing was performed using a tilling machine. In addition, the film wrapped around the cultivator, and the film could not be plowed.

[0036]

According to the present invention, an agricultural mulching film comprising a biodegradable resin is used after the end of its use period.
Promotes biodegradation and enables short-term degradation,
It is possible to provide a landfill disposal method in which biodegradability does not vary much depending on the climatic climate, soil quality, season, etc. of the landfill disposal area, and can be thrown into the soil as it is laid and disposed.

Continuing on the front page (72) Inventor Toru Tsukahara 2-5-2, Marunouchi, Chiyoda-ku, Tokyo Within Mitsubishi Chemical Co., Ltd. F term (reference) 4B065 AA01X AA41X AA58X AA66X AC20 BA22 BB09 BB40 BD44 CA55 4F301 AA25 AB01 CA09 CA23 CA38

Claims (8)

[Claims] Claims: 1. An agricultural mulching film made of a biodegradable resin is disposed of by landfilling, and a compound or / and a microorganism having the resolution of the biodegradable resin constituting the film is applied to the surface of the mulching film in the laid state. A method of disposing of a mulching film for agricultural use, wherein the film is buried by plowing the film into the soil after contact. 2. The method according to claim 1, wherein the biodegradable resin constituting the agricultural mulching film is an aliphatic or alicyclic polyester resin. 3. The structural unit 3 wherein the aliphatic or alicyclic polyester resin is derived from an aliphatic or alicyclic diol.
5 to 49.99 mol%, 35 to 49.99 mol% of a structural unit derived from an aliphatic or alicyclic dicarboxylic acid, and 0.02 to 30 mol of a structural unit derived from an aliphatic or alicyclic oxycarboxylic acid % Of the agricultural mulching film according to claim 2. 4. The structural unit derived from an aliphatic or alicyclic diol is a unit derived from an aliphatic diol having 2 to 10 carbon atoms or a unit derived from an alicyclic diol having 3 to 10 carbon atoms. The structural unit derived from an aliphatic or alicyclic dicarboxylic acid is a unit derived from an aliphatic dicarboxylic acid having 2 to 12 carbon atoms or an alicyclic dicarboxylic acid having 3 to 12 carbon atoms. Disposal method for agricultural mulching film. 5. The agricultural mulching film according to claim 3, wherein the constituent unit derived from the aliphatic or alicyclic oxycarboxylic acid is a unit derived from a 2-hydroxyalkanoic acid having 2 to 12 carbon atoms. Waste disposal method. 6. A structural unit derived from an aliphatic or alicyclic diol is a unit derived from 1,4-butanediol, and a structural unit derived from an aliphatic or alicyclic dicarboxylic acid is derived from succinic acid. The disposal method for an agricultural mulching film according to any one of claims 3 to 5, wherein the unit is a unit, and the constituent unit derived from an aliphatic or alicyclic oxycarboxylic acid is a unit derived from lactic acid or glycolic acid. 7. The disposal method for an agricultural mulching film according to claim 1, wherein the biodegradable resin constituting the agricultural mulching film has a number average molecular weight of 10,000 to 200,000. 8. The agricultural mulching according to any one of claims 1 to 7, wherein the compound and / or microorganism having the ability to degrade biodegradable resin constituting the agricultural mulching film is a hydrolase or an oxidative enzyme. Film disposal method.