JP2005176681A - Method of using agricultural mulching film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of using an agricultural mulching film for not merely saving labor of farm work but also reducing load to the environment. <P>SOLUTION: This method of using the agricultural mulching film comprises using a film obtained by formulating a resin component comprising a polymer (A) mainly made from diol and dicarboxylic acid and a polymer (B) made from oxycarboxylic acid with calcium carbonate (C) so as to have desired biodegradability and photodegradability, and plowing film pieces in soil after a given period expires. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of using an agricultural mulching film, and more specifically, after use as in a conventional agricultural mulching film, the used film is collected from a mulched portion such as a field and disposed of by incineration. The present invention relates to a method for using agricultural mulching film for covering crops and the like without particularly burdening the environment.

  As a film that can be used as an agricultural mulching film, for example, Patent Document 1 proposes a photo-disintegrating mulching film. This film is obtained by blending calcium carbonate with polyolefin. Although it is proposed to be used, it has been reported that crushing is much easier than in the case of polyolefin alone. According to the patent document, this easy crushability is based on the fact that a homogeneous film made of polyolefin and calcium carbonate is deteriorated by light or heat. Further, Patent Document 2 discloses an agricultural covering film in which a specific inorganic substance is mixed with a polyolefin-based resin and calcium carbonate is improved as a mulching film having photodisintegration property, thereby improving heat retention and the like. None of the films disclosed in these documents unfortunately have biodegradability, which is the desired performance, from the viewpoint of solving the waste problem of plastic films. Therefore, there is a problem in the disposal method after use as a mulching film, and the user cannot be released from the duty of collecting the film after use.

  On the other hand, Patent Document 3 proposes a biodegradable film containing an aliphatic polyester polymer as a component. This film is a film that disintegrates under the action of microorganisms in soil or water. However, since this film uses an aliphatic polyester as a film polymer and is expensive, its use is extremely limited, and although it has biodegradability, it has photodegradability. There is a problem in disassembling the product by using it in the field after use, etc., because it is not available, etc., and there is a problem. Agricultural mulching with reduced environmental load and user workload. There is a problem that it cannot be said to be sufficient for use as a film.

  Further, Patent Document 4 proposes a packaging film made of polylactic acid, polyglycolic acid, or the like that is completely decomposed when left in the soil or the like. The film disclosed in this Patent Document Because it has excellent biodegradability even if it is left in the soil after use or discarded in water, it does not cause various obstacles due to film fragments remaining in the soil after use. Although it is excellent as an agricultural mulching film, there is a problem in the film strength at the time of use, and there is a practical problem as an agricultural mulching film. In addition, since it does not have photodegradability, it is good to use it as an agricultural mulching film as well as a film that can provide a method of use that can fully meet the needs of the user, similar to the film disclosed in Patent Document 3. I can not.

  Patent Document 5 proposes a biodegradable film or sheet obtained by blending the polylactic acid polymer described in the above document with a biodegradable aliphatic polyester having a glass transition point of 0 ° C. or less. According to the patent document, it is reported that the impact resistance is improved by blending a biodegradable polyester other than the polylactic acid-based polymer, but if it is left at a temperature slightly higher than room temperature, it will stretch and heat. The seal strength and the like change with time, and it is still considered that there is a problem that the strength is not sufficient for use as an agricultural film.

Patent Document 6 contains a polylactic acid polymer and another aliphatic polyester in a polymerization ratio of 80:20 to 20:80, and the heat of fusion in terms of the polylactic acid polymer is 35 J / g or less. A biodegradable film is proposed, and according to the patent document, it is reported that the film is excellent in flexibility, transparency and heat sealability. However, even in the case of this film, although the properties of the biodegradable film are secured to some extent, in addition to being expensive, in terms of physical properties such as the tear strength and dart strength of the film, when viewed from the actual use scene Further improvement is required, and it is not yet sufficient for use as an agricultural mulching film because it does not have photodegradability.
Japanese Patent Publication No.52-31256 JP-A-56-72035 JP 11-349706 A JP-A-6-256480 JP-A-9-111107 JP-A-11-222528

  An object of this invention is to provide the usage method of the agricultural mulching film in which the load to the environment was further reduced.

  In order to solve the above-mentioned problems, the present inventor uses a film in which the cultivation period of cultivated crops, foliage plants, etc., and the balance between photodegradability and biodegradability are balanced as a result of intensive studies. After the passage of the coating period, find that the agricultural mulching film usage method can achieve the above-mentioned purpose, including making the photocollapsed film into the soil and using it as part of the microbial carbon source, The present invention has been completed. As a film that can be used for such applications, as a raw material composition disclosed in Japanese Patent Application No. 2003-380116 filed by the present applicant, a polymer (A) mainly composed of a diol and a dicarboxylic acid, and an oxycarboxylic acid are used. The film obtained by mix | blending calcium carbonate (C) with the resin component which consists of a polymer (B) is mentioned.

  That is, the present invention, after a predetermined period of time, photo-collapsed agricultural mulching film, plunged small pieces of mulching film photo-collapsed together with the remains of crops such as roots into the soil, biodegraded in the soil, It is related with the agricultural mulching film usage method which consists of making it lose | disappear. If the plant to be mulched is a variety of crops, use a tractor equipped with a rotary to harvest the crop. Needless to say, it may be poured into the soil. In addition, as a film which can be suitably used for such a method of use, a polymer component (A) mainly composed of diol and dicarboxylic acid, and a resin component composed of polymer (B) composed of oxycarboxylic acid and heavy calcium carbonate (C) Thus, an agricultural mulching film having a thickness of 10 to 50 μm can be mentioned.

  The photodisintegrated film piece is very thin with a thickness of 10 μm to 50 μm, so there is no major obstacle when it is infiltrated into the soil. As a result, there is virtually no impact on the next crop. Of course, since it is not necessary to collect the photodisintegrated film pieces, not only can the efficiency of farming be improved, it can greatly reduce the burden on the environment, but also the mulching film left on the soil surface without being collected. A part of the sword does not flow into the river with rainwater or be blown away by the wind.

  More specifically, the film usable in the present invention includes a polymer component (A) mainly composed of diol and dicarboxylic acid, and a resin component composed of a polymer (B) composed of oxycarboxylic acid and heavy calcium carbonate (C). And the polymer (A) accounts for 60 to 95% by mass, the polymer (B) accounts for 5 to 40% by mass, and the heavy calcium carbonate has an average of 0.1 to 10 μm. A film having a particle size and having a thickness of 10 to 50 μm, which is a mixture of the heavy calcium carbonate at a ratio of 5 to 150 parts by mass with respect to 100 parts by mass of the resin component. It is done. Although it depends on the type of crops used and the cultivation method, etc., it is usually photodegradable (the number of days required for the stretched film to have a tensile elongation of 50%) 20 to 100 days, biodegradable (photodegradable) When the received film is embedded in soil, the number of days required for 50% to disappear is preferably within the range of 10 to 60 days. Needless to say, it is necessary to select and use a film formed by adjusting the amount of each component to satisfy such a condition.

  According to the method for using the agricultural mulching film according to the present invention, the agricultural mulching film can be lost by biodegrading in the soil after being immersed in the soil, so that the load on the environment can be reduced. Instead, the effect of increasing the efficiency of farm work will be exhibited.

  The present invention will be specifically described below. The method of using the agricultural mulching film according to the present invention is to collect the photo-degraded agricultural mulching film in the soil after a predetermined period of time and recover the used film by biodegradation in the soil. The present invention relates to a method for using an agricultural mulching film. Here, after the lapse of a predetermined period, after the mulching, after the cultivating period of the covered crop, or after the lapse of the period when the growing condition of the covered crop or the growing environment does not require mulching. The period is determined in consideration of the photodisintegration property of the film used and the cultivation period of the covered crop. This period varies depending on the type of crop to be covered, the cultivation method, and the like, but is usually 3 months to 4 months. In addition, pour-in only has to follow normal agricultural practices and does not require special consideration.

  The polymer (A) used for production of the mulching film used in the present invention is a polymer mainly composed of a diol and a dicarboxylic acid. The diol constituting the polymer (A) is, for example, an aliphatic alcohol component, and aliphatic diols such as ethylene glycol, butanediol, hexanediol, octanediol, cyclopentanediol, cyclohexanediol, and cyclohexanedimethanol, or these And derivatives thereof. In particular, those having a bifunctional compound having a C 2-10 alkylene group or cycloalkylene group as a main component are preferred. The diol constituting the polymer (A) is an aliphatic alcohol component, for example, an aliphatic diol such as ethylene glycol, butanediol, hexanediol, octanediol, cyclopentanediol, cyclohexanediol, cyclohexanedimethanol, Or these derivatives are mentioned. In particular, those having a bifunctional compound having a C 2-10 alkylene group or cycloalkylene group as a main component are preferred.

  The polymer (A) shown above is obtained by condensation polymerization by selecting one or more kinds from the above raw materials. If necessary, the target polymer may be obtained by increasing the molecular weight with an isocyanate compound or the like. The polymer (A) may be used alone or in a blend of two or more. Here, the polymer (A), that is, the aliphatic polyester has a weight average molecular weight of 60,000 to 600,000, preferably 100,000 to 400,000, and practical physical properties are obtained when it is less than 60,000. When it exceeds 600,000, the melt viscosity becomes high and the moldability may be deteriorated.

  In particular, suitable aliphatic polyesters include polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene adipate and their copolymers, and (1,4-butanediol, succinate adipate). , Lactic acid) copolymers. Moreover, the said polymer (A) has biodegradability, and as a usage-amount, it is the range of 60-95 mass% of the whole resin component, Preferably, it is 70-90 mass%, 60 mass If it is less than%, the elongation as a film is lowered, and the film becomes brittle and may not be suitable for use. On the other hand, if it exceeds 95% by mass, the stiffness of the film is lowered, and the film may be stretched more than necessary during stretching, which is not preferable.

  The polymer (B) which is the other component of the resin component of the mulching film used in the present invention is a polymer comprising oxycarboxylic acid. Polylactic acid, polyglycolic acid, poly (2-oxybutyric acid) and the like can be mentioned, but are not limited thereto. The polylactic acid-based polymer may be a homopolymer of L- or D-lactic acid, a copolymer of L- and D-lactic acid, and contains other hydroxydicarboxylic acid units as a small amount copolymerization component. It may be a copolymer. In addition, these homopolymers or copolymers may contain a small amount of chain extender residues.

  As the polymerization method, any known method such as a condensation polymerization method or a ring-opening polymerization method can be used. For example, in the condensation polymerization method, polylactic acid having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid or a mixture thereof.

  In the ring-opening polymerization method, polylactic acid can be obtained from lactide, which is a cyclic dimer of lactic acid, using a polymerization regulator or the like, if necessary, under a specific catalyst. Lactide includes L-lactide, which is a dimer of L-lactic acid, and D-lactide, which is a dimer of D-lactic acid. These can be mixed arbitrarily and polymerized to obtain a characteristic polylactic acid. it can.

  For the purpose of increasing the molecular weight, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound, and an acid anhydride can be used. The weight average molecular weight of the polymer (B) is preferably 60,000 to 600,000. When the weight average molecular weight is less than 60,000, practical physical properties as a film may not be expressed. In doing so, the melt viscosity becomes too high, and the workability may decrease, which is not preferable.

  Since the polymer (A) mainly composed of diol and dicarboxylic acid has a faster decomposition rate than the polymer (B) composed of oxycarboxylic acid, the amount of the polymer (B) in the resin component is adjusted by adjusting the blending amount. The biodegradation rate as a film is controlled in consideration of the period of covering with a film such as the cultivation period of the covered crop and the cultivation environment. In other words, it is preferable to select and use a film in which the amount of both is adjusted in consideration of the decomposition rate such as the cultivation period and cultivation environment.

  In the case of the film used in the present invention, the blending amount of the polymer (B) composed of the oxycarboxylic acid is 5 to 40% by mass, preferably 10 to 30% by mass, based on the entire resin component. If it is less than 5% by mass, it may be difficult to adjust the biodegradation rate as desired, which is not preferable. On the other hand, if it is added in excess of 40% by mass, the effect of slowing the biodegradation rate becomes remarkable, but a sufficient strength cannot be obtained, resulting in a hard film, which may cause problems in use.

  In the case of the film used in the present invention, the calcium carbonate (C) added to the resin component is heavy calcium carbonate having an average particle size of 0.1 to 10 μm, and this is mainly composed of a polymer composed of a diol and a dicarboxylic acid ( A) and 5 to 150 parts by weight, preferably 10 to 100 parts by weight, of the total resin component composed of the polymer (B) composed of oxycarboxylic acid is used at the time of use. It is preferable to select and use a film to which an appropriate amount is added according to the cultivation environment and the like because it can impart photodisintegration property, heat retention and the like, and can increase the biodegradation rate of the film. .

  That is, by adding the calcium carbonate (C) to the two resin components, the polymer (A) and the polymer (B), and forming a mulching film, the hydrophilicity is increased and the affinity for microorganisms is increased. As a result, the biodegradability as a film is promoted, and sufficient biodegradability is exhibited even if it is put into the soil or used as a part of compost raw material. It is guessed.

  Further, when the blending amount of calcium carbonate with respect to 100 parts by mass of the total resin component is less than 5 parts by mass, not only the mulching film can be provided at an acceptable price as an agricultural product, but also the desired photodegradable properties. You will not be able to get. Furthermore, the desired biodegradation rate cannot be achieved. On the other hand, if it exceeds 150 parts by mass with respect to 100 parts by mass of the total resin component, a film that is sufficiently satisfactory in terms of price and photodisintegration can be formed, but the moldability is poor and sufficient film strength cannot be obtained. Therefore, it is not preferable from the viewpoint of use as a mulching film.

  The film used in the method for using the agricultural mulching film according to the present invention has a thickness of 10 to 50 μm. If the thickness is less than 10 μm, sufficient film strength may not be obtained. On the other hand, if the thickness exceeds 50 μm, the photodegradability of the film and biodegradability when used as a part of compost raw materials This may cause a problem in that respect, and is not preferable.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. In the following examples, as a raw material composition disclosed in Japanese Patent Application No. 2003-380116 filed by the applicant of the present application, a polymer (A) mainly composed of a diol and a dicarboxylic acid, and a polymer (B A mulching film having a thickness of 20 μm obtained by blending calcium carbonate (C) with a resin component consisting of

(Example 1: Sweet corn)
At the end of April, using a marcher, the erection work and the stretching of the film were performed at the same time, and after drilling at a predetermined interval, raw corn was sown in the same hole. After harvesting sweet corn in late July, a piece of film that had been photodisintegrated along with the remains of sweet corn was placed in the soil using a tractor equipped with a rotary. At the time of squeezing, the film was cut into pieces, and there was no entanglement of the rotary blade and shaft part of the film. After 60 days from dredging, the soil was dug up and the remaining state of the film strip was investigated, but no residue was found. In the case of sweet corn, the side roots coming out from the bottom of the stalk penetrate the mulching film, and after harvesting it becomes difficult to peel off the film. For polyethylene mulching film, the film is removed before the side roots come out. So, it did not require any work to remove the mulching film, and it was extremely labor-saving.

(Example 2: Spring lettuce)
At the end of April, using a marcher, the erection work and the stretching of the film were performed at the same time. After drilling at predetermined intervals, lettuce seedlings were planted in the same hole. After harvesting lettuce in early July, we put the film with lettuce debris into the ground with a tractor equipped with a rotary. At the time of squeezing, the film was cut into pieces, and there was no entanglement of the rotary blade and shaft part of the film. After 60 days from dredging, the soil was dug up and the remaining state of the film strip was investigated, but no residue was found. When a polyethylene mulching film was used, the film was usually removed before squeezing, but in this example, the mulching film was not removed at all, and the labor saving was extremely high.

(Example 3: Japanese radish)
At the end of March, using a mulching film perforated at a predetermined interval in advance, the mulching film with a seeder was erected, and the film was spread and seeded at the same time. After harvesting radish in early June, the radish wreckage and the film were put into the ground with a tractor equipped with a rotary. At the time of squeezing, the film was cut into pieces, and there was no entanglement of the rotary blade and shaft part of the film. After 60 days from dredging, the soil was dug up and the remaining state of the film strip was investigated, but no residue was found. When a polyethylene mulching film was used, the film was usually removed before squeezing, but in this example, the mulching film was not removed at all, and the labor saving was extremely high.

(Example 4: Autumn and winter taro)
In late March, after seedlings were planted in Takatsuki, the film was stretched using a marcher. At the time of germination about 30 days after the planting, the film immediately above the bud was cut and allowed to sprout on the ground. In order to avoid high temperature drying of the roots in accordance with the practice in late June, soiling was performed. In late November, harvesting was carried out with a digger, but the film did not interfere with digging at all due to light decay and biodegradation. After digging work, plowing was carried out with a tractor equipped with a rotary, but there was no entanglement of the rotary blade and shaft part of the film, and the soil was dug up 30 days after the plowing, and the remaining state of the film fragments was checked. A survey was conducted, but no residue was found. In order to make it easy to reach the roots of top fertilizer components, rainwater, etc., when using a polyethylene mulching film, the film is usually removed before soiling, but in this example, it is absolutely necessary to remove the mulching film. However, it was extremely labor-saving, and good quality and yield could be obtained.

(Example 5: Pumpkin)
In mid-April, the film was stretched at the same time as the erection work using a marcher, and after drilling at predetermined intervals, pumpkin seedlings were planted. In mid-May, the vine that began to grow on the film was regarded as one parent vine, and the film was also spread on the vine's extension site to attract the vines. After harvesting the pumpkins in mid-July, the film was left in the field and plowed and cultivated by the rotary, but the film was chopped smoothly without any tangling of the rotary blade and shaft. After 60 days of dredging, the film piece in the soil was investigated, but no residue was observed. When a polyethylene mulching film is used, the film is usually removed before squeezing, but in this example, the mulching film was not removed at all, and the labor saving was very high.

(Example 6: watermelon)
In mid-May, the film was spread at the same time as setting up with a muller, punched at predetermined intervals, and then planted watermelon seedlings. It was tailored so that 4 vines were produced from 1 strain, and a film was stretched in the direction of extension of the vines in mid-June and attracted branches (vines). After harvesting in early August, plowing and plowing with a rotary were performed with the film left in the field, but the film was chopped smoothly without any entanglement of the rotary blade and shaft. After 60 days of dredging, the film piece in the soil was investigated, but no residue was observed. When a polyethylene mulching film is used, the film is usually removed before squeezing, but in this example, the mulching film was not removed at all, and the labor saving was very high.

(Example 7: groundnut)
At the end of May, the film was stretched at the same time as staking with a Malcher, perforated at predetermined intervals, and then sown. Since the film of the present invention has both photodisintegration and biodegradability, it is easy to enter the ovary pattern even when the film is stretched at the time of entering the ovary pattern peculiar to peanuts, and the entry rate is It was almost 100%. When using a polyethylene mulching film, it is difficult to enter the ovary pattern into the soil if it is stretched, so it is necessary to remove the film before flowering at the expense of maintaining the soil temperature and controlling weeds, which are important for growth. . The film of the present invention in which the ovary pattern can enter while being stretched can sufficiently exhibit the original effects of the multi-film until the harvest period, and can save the work of removing the film. Although harvested by a digger in early November, the film did not interfere with the digging work due to light decay and biodegradation. After digging work, plowing was carried out with a tractor equipped with a rotary, but there was no entanglement in the rotary of the film, and after 60 days from plowing, the soil was dug up and the remaining state of film fragments was investigated. Was not recognized.

(Example 8: sweet potato)
In mid-May, the film was stretched at the same time as the setting by a muller, punched at predetermined intervals, and then planted sweet potato seedlings. The film used was a black colored film for the purpose of controlling weeds. Harvesting with a potato digger in early October had no hindrance to the digging work. When polyethylene mulching film is used, the film is usually removed before digging in order to proceed smoothly, but in this example, the mulching film removal work is not required at all and it is extremely labor-saving. Was expensive. After digging work, plowing was carried out with a tractor equipped with a rotary, but the film was not entangled with the rotary, and after 60 days from plowing, the soil was dug up and the remaining state of the film fragments was investigated. Was not recognized.

  According to the present invention, by using a film having specific properties as an agricultural mulching film, in the case of polyethylene mulching film, depending on the type of crop and the cultivation system, the film is removed before harvesting, etc. In addition to not requiring such removal work, it is not only possible to leave it until the completion of harvesting, but also when plowing the field after the harvesting work, as preparation work for the cultivation of the next crop, etc. Because it is possible to break down the light-collapsed film pieces into the soil, it can be decomposed in the soil, which not only greatly reduces the work burden on the grower, but also about the removed film This eliminates the need for post-treatment such as combustion of sewage, thus providing a way to use agricultural mulching film with less environmental impact. It and will, contribute to the preservation of the global environment is highly expected.

Claims (5)

  Heavy calcium carbonate (C) in an amount sufficient to impart the desired biodegradability to the resin component consisting mainly of the polymer (A) consisting of diol and dicarboxylic acid and the polymer (B) consisting of oxycarboxylic acid A method for using an agricultural mulching film, comprising: adding a slag, processing the resulting mixture into a film having a predetermined thickness, and covering the target soil surface with the film.   The resin component consisting mainly of a polymer (A) consisting of a diol and a dicarboxylic acid and a polymer (B) consisting of an oxycarboxylic acid comprises 60 to 95% by mass of the polymer (A) and 5 to 40% by mass of the polymer (B And the amount of the heavy calcium carbonate sufficient to impart the desired biodegradability is a ratio of 5 to 150 parts by mass with respect to 100 parts by mass of the resin component, The method for using an agricultural mulching film according to claim 1, wherein the calcium has an average particle diameter of 0.1 to 10 µm, and the predetermined thickness is 10 to 50 µm.   The polymer (A) mainly composed of diol and dicarboxylic acid is polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, or (1,4-butanediol, adipate succinate, lactic acid) copolymer Item 3. A method for using the agricultural mulching film according to Item 1 or 2.   The method for using an agricultural mulching film according to any one of claims 1 to 3, wherein the polymer (B) comprising the oxycarboxylic acid is polylactic acid, polyglycolic acid, or poly (2-oxybutyric acid).   The method for using an agricultural mulching film according to any one of claims 1 to 4, further comprising pouring the agricultural mulching film into the soil after elapse of a predetermined period after use for covering the soil surface.