JP2000092922A - String like-structured material for direct sowing of rice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject structured material consisting essentially of a biodegradable raw material, enabling the simplification of a conventional agricultural method and the work saving, industrially easily and at a low cost by containing husked rice in a specific part thereof. SOLUTION: This string like structured material for direct sowing of rice, consists of essentially a biodegradable material, and has a part 1 of a high strength-keeping rate and a part 2 having a low strength-keeping rate alternately. The part 1 having a high strength-keeping rate is a cylindrical structured material having up to 3 mm thickness, and at least one grain of a husked rice is contained in the part 1 having the high strength-keeping rate. In this case, the part 1 having the high strength-keeping rate is preferably a fiber consisting mainly of a polylactic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cord-like structure made of a novel material for direct sowing of rice.

[0002]

2. Description of the Related Art Rice cultivation is a typical industry unique to Japan.
Although it is one of the few self-sufficient agricultural products, it is also an industry that is considered to be extremely difficult to maintain in the future due to the recent liberalization of the global market, domestic economic conditions, and the status of workers such as successors. . In addition, the shortage of workers and the sharp decline in the number of young workers in agricultural management have forced mechanization, and small and medium-sized farmers have become extremely burdened with the payment of machinery, making it a stable and sustainable process. It is difficult to manage.

[0003] In order to maintain rice cultivation, direct sowing has been tried as an introduction of mechanization and automation by consolidating and increasing the scale of farmland and reforming agricultural methods, but the effect is not sufficiently enhanced at present. . In particular, farmers who are difficult to increase the scale of the problem are becoming more and more serious, and the aging of the farmers and leaving the farms without successors are progressing. In addition, in large-scale agriculture, it is difficult to obtain rice with good taste. On the other hand, the use of pesticides and fertilizers is increasing more and more in order to increase the yield, which contributes to cost increase and pollution of groundwater and downstream water bodies and environmental destruction.

[0004]

The present inventors have made intensive studies and completed the present invention. That is, an object of the present invention is to propose an epoch-making string-like structure for direct sowing that enables simplification and labor saving of the current farming method industrially easily and inexpensively.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a biodegradable material, in which portions having high strength retention and portions having low strength retention in the soil are present alternately in the longitudinal direction. The portion having a high strength retention is a tubular fiber structure having a mesh size of at most 3 mm, and the portion having a high strength retention is a string-like fiber structure for direct sowing of rice in which at least one grain of rice is included. .

The tubular fiber structure used in the portion of the present invention having a high strength retention in the soil is a tubular woven fabric or a tubular (circular knit).
A knitted product, a product obtained by forming a normal woven or knitted product into a tubular shape, a braided structure, or a product obtained by forming a nonwoven fabric such as a spun bond into a tubular shape can be used. The inner diameter of the tubular fiber structure may be such that the rice firs enter and can be almost fixed, but is preferably at most 3 mm, more preferably at most 2 mm, particularly preferably at most 1.5 mm. It is preferable to be somewhat tight. Particularly, a tubular woven fabric, a tubular knitted fabric, or a braided structure naturally generates a tightening force, which is preferable.

[0007] In the case of continuously manufacturing a portion having a high strength retention and a portion having a low strength retention in the soil, the size is the same, but a portion having a high strength retention and a portion having a low strength retention are separately formed, and later. When connecting, the size of each cylinder is not particularly limited. However, in consideration of workability, cost, and decomposability in soil, it is preferable that the area is equal to or smaller than a portion having a high strength retention.

[0008] The mesh size of the cylindrical material in the portion having a high strength retention rate in the soil needs to be large enough to hold rice fir therein and hold it. It must be large enough to prevent roots and shoots from growing. Usually at most 3 mm, preferably at most 2 mm,
More preferably, it is 0.2 to 1.5 mm. If the mesh size is wider than 3 mm, there is a possibility that the rice fir will fall off, and that sparrows, crows and other birds may pike the rice fir in the string. Further, when the mesh size is smaller than 0.2 mm, there is a problem in sprouting and rooting, which is not preferable.
The term “mesh” here refers to the size of the fit at the portion where the rice fir is put when the rice fir is put into the tubular structure.

The portion having a high strength retention in the soil is essentially biodegradable but has a relatively high strength retention in the soil. In view of the above, a fiber mainly containing polylactic acid is preferable.

The polylactic acid used in the present invention refers to a lactic acid copolymer containing a polymer of lactic acid and a copolymerizable monomer, and preferably has a molecular weight of 80,000 or more, more preferably 100,000 or more, and particularly preferably 10 to 100. 250,000.

Polylactic acid may be a single polymer, but may be copolymerized with other monomers, oligomers and the like. For example, (a) hydroxyalkyl carboxylic acid such as glycolic acid, hydroxybutyl carboxylic acid, etc., (b) aliphatic lactone such as glycolide, lactide, butyrolactone, caprolactone, (c) ethylene glycol, propylene glycol, butanediol, hexane Aliphatic diols such as diols, (d) oligomers of polyalkylene ethers such as diethylene glycol, triethylene glycol, ethylene / propylene glycol, dihydroxyethylbutane, etc., and polyalkylene glycols such as polyethylene glycol, polypropylene recall and polybutylene ether , (E) polypropylene carbonate, polybutylene carbonate, polyhexane carbonate, polyoctane carbonate, polydecane car Components derived from aliphatic polyester polymerization raw materials, such as polyalkylene carbonate glycols such as acrylates and oligomers thereof, and (f) aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. The main component, that is, 50% by weight or more (especially 60% or more), and a homopolymer of an aliphatic polyester, a block or / and random copolymer of an aliphatic polyester, and other components in the aliphatic polyester, For example, copolymers and / or mixtures of aromatic polyesters, polyethers, polycarbonates, polyamides, polyureas, polyurethanes, polyorganosiloxanes and the like copolymerized in an amount of 40% by weight or less, preferably 30% by weight or less (block or / and random) All For free.

Also, a small amount of D-lactic acid may be contained in L-lactic acid. In particular, the amount of the D-form is 0.5% for imparting flexibility to the fiber, adjusting the melting point and decomposability, and adjusting the spinning temperature.
% Or more, more preferably D-
Body mass is 0.7-1.5%.

When the polylactic acid is melted, lactide (monomer) and its low polymerization degree (oligomer) remain in the polymer, and the remaining monomer and low molecular weight oligomer are operable at the time of fiber production and obtained. It affects the physical properties and quality of the fiber, and its amount is preferably 10% by weight or less,
It is more preferably at most 1% by weight, most preferably at most 1% by weight. However, although the reasons for the remaining monomers and oligomers are unknown, they are effective in promoting the germination and rooting of plants, and it is particularly preferable that 0.1 to 0.7% by weight is left in the fiber.

In order to enhance the stability of the obtained polylactic acid, an antioxidant is added when the polymerization of the polylactic acid proceeds.
For example, about 0.1 to 3% by weight can be additionally mixed. As the antioxidant, hindered phenol, hindered amine and other known ones are used. The addition rate is about 10 to 30,000 ppm, particularly 50 to 10,000 ppm.
ppm is preferred. If necessary, a light-proofing agent such as an ultraviolet absorber, a matting agent such as titanium oxide and magnesium oxide, and various organic and inorganic pigments such as carbon black can be added.

These matting agents and pigments can be added at any time during the polymerization or spinning of polylactic acid, but it is more preferable to add them immediately before spinning. In particular, by coloring the polylactic acid fiber to black, brown, brown or gray, etc. close to the color of the soil, after cutting the rice at the time of installation in the field or harvesting,
Even if it remains, there is no particular discomfort.

As other additives, heat stabilizers, light stabilizers, water repellents, hydrophilizing agents, lubricants and the like can be appropriately added depending on the purpose and application. In particular, water repellents and hydrophilizing agents are important in terms of controlling biodegradability.

The polylactic acid fiber may be a monofilament composed of one fiber or a multifilament composed of a plurality of fibers. The fineness of the polylactic acid fiber is not particularly limited, but is usually 100 denier or more, preferably 200 denier or more, and more preferably 300 to 100.
It is 0 denier. When the thickness is smaller than 100 denier, workability and yield are deteriorated in manufacturing a string-like structure by knitting. On the other hand, if it is larger than 1000, not only is the material used more than necessary, but the string-like structure becomes hard, and it becomes somewhat difficult to insert rice fir into it, which is not economically preferable.

The fineness of each filament constituting the multifilament is usually at least 1 denier, preferably at least 1.5 denier, more preferably at least 3 denier. If the denier is less than 1 denier, not only does the productivity of the fiber decrease, but it also has an unfavorable effect on the germination and rooting of the rice.

In the case of multifilaments, it is preferable to twist the filaments so that each filament is not separated. As the number of twists, a degree of sweet twist represented by ordinary multifilaments is sufficient, but medium twist or strong twist may be used. For example, if the denier is 200 denier and the number of twists is at most 2 to 500 turns / m, the purpose can be sufficiently achieved. In other words, one standard is a number of twists × deniers of at most about 100,000. It is to be noted that any number larger or smaller than this can be adopted as long as it meets the purpose.

The polylactic acid fiber is produced by a conventional method for producing a monofilament or a multifilament. Preferably, the fiber has a heat of fusion of at least 15 joules / g, which indicates the crystallinity of the obtained fiber. 20
Joule / g, more preferably 25 joule / g. If the heat of fusion is less than 15 joules / g, the fiber will have insufficient crystallinity, and will have insufficient strength and strength. In particular, when a knitted string-like structure is manufactured, the workability and the yield are reduced, and the form stability and heat stability of the string-like structure are reduced, which hinders germination and rooting of rice.

The fiber having a low strength retention in the soil may be a fiber which is retained in the soil for 6 months and has a strength retention lower than that of the polylactic acid fiber. It is at most 80%, more preferably at most 70%, particularly preferably at most 60%. When the retention rate is higher than 80%, the string-like structure of the present invention remains after harvesting, and becomes an obstacle when digging a field with a cultivator or the like. In other words, if the string containing the rice fir remains with high strength in the length direction, it may be wrapped around the rotating teeth of the tilling machine or cause troubles when digging by the cultivator.

As the fiber having a low strength retention in soil used in the present invention, preferably, the strength retention after standing for 6 months in the soil is at most 80% of the strength retention of the polylactic acid fiber used in the present invention. Yes, eg biologically produced PHB, PH
(V / B) (eg, Monsanto Biopol), polybutylene succinate, polyethylene succinate.
Fibers manufactured from adipate (for example, Showa Kogyo Co., Ltd. Bionole), polycaprolactone (for example, UCC Tone), rayon, acetate, polyvinyl alcohol, polyvinyl alcohol derivatives, etc., and one or more of them are used. You can do it. The shape of the fiber is not particularly limited as long as it is the same as the above-mentioned polylactic acid fiber.

When used in combination with natural fibers,
It is preferable in terms of cost reduction and control of degradability, and it is particularly preferable to use a blended yarn as a short fiber since the criticality of decomposition can be clarified. When short fibers are used, the thickness of the fibers is set to a thickness corresponding to the above-described denier.

The strength of the cord-like structure may be such that it can be pulled by a human or a machine into the field, and is preferably at least 0.5 kg, more preferably at least 1 kg.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples,
Unless otherwise specified,% and parts are parts by weight and parts by weight.

Example 1 L-lactic acid / D-lactic acid = 99.
Melt spinning was performed at a spinning temperature of 220 ° C. using polylactic acid having a weight average molecular weight (Mw) of 135,000 consisting of 5 / 0.5 to obtain a 200d / 12f multifilament. The strength was 3.3 g / d and the elongation was 35%. In addition, commercially available aliphatic polyester (SUNKYONG INDUST)
Spinning was performed at 210 ° C. using RIES SG1111) to obtain a 150d / 36f multifilament. The strength was 3.1 g / d and the elongation was 41%. Each filament was twisted at 350 turns / m. Using each thread, warp and weft density each 150 mesh (150
Per inch) to produce a 2 mm diameter tubular woven fabric.

Next, a tubular fabric using polylactic acid fibers was cut into a length of 10 cm, and a tubular fabric using aliphatic polyester fibers was cut into a length of 10 cm. The present invention forms a long string by attaching one rice husk to the center of the tubular woven fabric using polylactic acid fibers at approximately the center and then alternately connecting the tubular woven fabric and the tubular woven fabric using aliphatic polyester fibers. A string-like fiber structure for direct sowing of rice was produced.

The string-like fiber structure was placed on the surface of soil, and water was laid on the soil so as to have a depth of 1 cm. Water was changed once every two days. After 6 months, the fiber structure was taken out and the strength was measured, whereupon the polylactic acid fiber portion was 91% of the initial strength and the aliphatic polyester fiber portion was 58% of the initial strength.

<Example 2> A tubular fabric using the polylactic acid fiber of Example 1 was cut into a length of 10 cm. Example 1
Aliphatic polyester fiber into three strands, 12c
The tubular fabrics were tied continuously so that rice fir enters at m intervals. As in Example 1, the strength of each part was measured after standing for 6 months. Polylactic acid fiber part is 90% of initial strength
And the portion of the aliphatic polyester fiber has an initial strength of 5%.
7%.

Example 3 L-lactic acid / D-lactic acid / polyethylene glycol (number average molecular weight 12000) = 91.7
Weight average molecular weight (Mw) 1 having a composition of /0.3/8.0
Using 25,000 polylactic acid, melt spinning was performed at a spinning temperature of 215 ° C. to obtain a 300d / 1f monofilament by a conventional method. The strength was 3.5 g / d and the elongation was 30%. In addition, a commercially available aliphatic polyester (SUNKYONG)
2 using INDUSTRIES SG1111)
Spinning was performed at 10 ° C. to obtain a multifilament of 100d / 18f. The strength was 3.0 g / d and the elongation was 43%. The filament was twisted at 400 turns / m.

Using each of the yarns, the warp / weft density is 150 mesh (150 yarns / inch) and the diameter is 1.5 mm.
Was manufactured. Next, the tubular fabric using the polylactic acid fiber was cut into a length of 10 cm, and the tubular fabric using the aliphatic polyester fiber was cut into a length of 10 cm. The present invention forms a long string by attaching one rice husk to the center of the tubular woven fabric using polylactic acid fibers at approximately the center and then alternately connecting the tubular woven fabric and the tubular woven fabric using aliphatic polyester fibers. A string-like fiber structure for direct sowing of rice was produced. As in Example 1, the strength was measured after 6 months. 85% of the initial strength of the polylactic acid fiber monofilament was retained, and the portion of the aliphatic polyester fiber was 55% of the initial strength.

[0032]

By using the string-shaped structure of the present invention,
The concept of conventional farming is completely changed, and sowing can be performed very efficiently and with reduced labor. In addition, there is no spillage or unevenness due to the presence of the firs in the string, and the excellent uprightness of the rice due to the string, and it can be knocked down by a little wind or current, It can germinate and grow very stably without being caught. In addition, the use of this cord structure may cause a phenomenon that the growth of rice is somewhat improved for unknown reasons. That is, the use of the string structure of the present invention not only saves labor but also increases the durability relatively against storm and flood damage after germination of rice, and is effective in improving growth and harvesting.

[Brief description of the drawings]

[Figure 1] String structure (woven fabric + woven fabric) according to the present invention

Fig. 2 String structure (woven fabric + string) according to the present invention

Fig. 3 String structure (woven fabric + nonwoven fabric) according to the present invention

[Explanation of symbols]

 1 High strength retention ratio 2 Low strength retention ratio 3 Joint

Claims (4)

[Claims] Claims: 1. A material which is essentially made of a biodegradable material, wherein portions having high strength retention in the soil and portions having low strength are alternately present in the length direction, and portions having a high strength retention in the soil are provided. A cord-shaped fibrous structure for direct sowing of rice, comprising a cylindrical fibrous structure having a mesh size of at most 3 mm, wherein at least one rice hull is included in a portion having a high strength retention. 2. The cord-like fiber structure according to claim 1, wherein the portion having a high strength retention in the soil is a fiber containing polylactic acid as a main component. 3. A portion having a low strength retention in soil is polyhydroxybutyrate, polyhydroxy (butyrate / valate), polybutylene succinate, polyethylene (succinate adipate), polycaprolactone.
2. The cord-like fiber structure according to claim 1, which is at least one kind of fiber comprising rayon, acetate, polyvinyl alcohol, and a polyvinyl alcohol derivative. 4. The cord-like fiber structure according to claim 2, wherein the polylactic acid fibers are colored brown, black or brown.