JP2002125484A - Biodegradable weed-proofing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weed-proofing sheet excellent in weed-proofing effect and workability, having sufficient water-permeable property and air permeability and high strength, capable of readily carrying out disposal treatment because of natural decomposition after use and not causing environmental pollution. SOLUTION: This weed-proofing sheet is obtained by using a woven fabric composed of a biodegradable thermoplastic resin fiber and the sheet is characterized in that a cover factor (K) represented by the following formula (1) [wherein Dp is warp fineness (decitex); Np is warp weave density (number/2.54 cm); ρp is warp specific gravity (g/cm3); Df is weft fineness (decitex); Nf is weft weave density (number/2.54 cm) and ρf is weft specific gravity (g/cm3)] in the woven fabric is 1,000 to 2,500.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weed control sheet, and more particularly to a weed control sheet suitable for use when planting or sowing various seedlings and seeds.

[0002]

2. Description of the Related Art In recent years, greening of parks, gardens, residential lands, open spaces, and the like has become active. Along with this, efforts have been made to prevent weeds for plant cultivation and preservation of aesthetics.In recent years, various methods have been used in recent years, in order to suppress the growth of weeds, in place of manual weed removal and use of herbicides. A grass sheet is used, and as a conventional grass sheet, a sheet made of a synthetic resin, a sheet made of an iron plate, a sheet made of paper, and the like are known.

However, when a sheet made of a synthetic resin or a sheet made of an iron plate is used, there is a problem that water due to rainfall or the like accumulates on the sheet surface because the sheet has no water permeability. Also, when planting with these weed control sheets, it is difficult to replenish the plants with water, and because the sheets do not have air permeability, the soil on the ground covered by the sheets is stuffy. There has been a problem that the soil temperature rises more than necessary, or air necessary for the growth of seedlings and seeds in the soil is not supplied, which adversely affects planting. In addition, since these sheets are not decomposed on the soil surface or in the soil, they have to be collected after use, which is not only time-consuming, but also disposing of unnecessary sheets after collection poses a problem in terms of environmental pollution. I was Further, when a paper sheet is used, the collection becomes unnecessary, and environmental pollution does not occur at the time of disposal, but there is a problem due to insufficient water permeability and air permeability as in the case described above. Was.

As a herbicidal sheet for solving such a problem, Japanese Patent Application Laid-Open No. H11-229260 proposes a herbicidal sheet formed of a nonwoven fabric made of a biodegradable thermoplastic aliphatic polyester resin. ing. Although this sheet substantially solves the above-mentioned problems, it may not always be sufficient in strength, and particularly when the sheet is nailed or fixed to the grass sheet, fixing of the struck portion or The tear resistance was not sufficient. Also,
In terms of workability, more excellent ones have been demanded.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide an excellent weed control effect, a sufficient water permeability and air permeability, and a high strength and excellent workability. Moreover, it is an object of the present invention to provide a herbicidal sheet which is easily decomposed because it is naturally decomposed after use and does not cause environmental pollution or the like.

[0006]

Means for Solving the Problems The present invention achieves the above object, and is a herbicidal sheet using a woven fabric made of biodegradable thermoplastic resin fibers, wherein the woven fabric has the following formula (1) ) Is 1
The gist of the present invention is a herbicidal sheet characterized by being 000 to 2,000.

[0007]

(Equation 2) Where D _p : warp fineness (decitex) D _f : weft fineness (decitex) N _p : warp weave density (book / 2.54 cm) N _f : weft weave density (book / 2.54 cm) ρ _p : warp specific gravity (g / cm) ³ ) ρ _f : Specific gravity of weft (g / cm ³ )

[0008] The present invention also provides a herbicidal sheet having a hole through which a seedling or a bud of a plant to be grown passes.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The weed prevention sheet of the present invention needs to be made of a woven fabric made of biodegradable thermoplastic resin fibers. The biodegradable thermoplastic resin is not particularly limited, but is preferably an aliphatic polyester resin that is biodegraded through hydrolysis, among which an aliphatic polyester resin synthesized from a diol component and a dicarboxylic acid component. Polymers are particularly suitable and include polylactic acid, polyalkylene alkanoates, poly β hydroxyalkanoates, and copolymers thereof.
In particular, polylactic acid is most preferable in consideration of heat resistance, mechanical properties, and the like. By using such biodegradable resin fibers, the sheet after a certain period of time is almost completely decomposed by the action of microorganisms, eliminating the need to remove and dispose of the sheet, as well as environmental pollution. This has the advantage of not producing The reason why polylactic acid is preferable is that polylactic acid fiber has higher rigidity than other biodegradable fibers, so that the spreadability of the weed prevention sheet is improved, and for example, it is easy to spread the weed prevention sheet during construction. No.

[0010] The biodegradable thermoplastic resin fiber (hereinafter sometimes abbreviated as biodegradable resin fiber) is not particularly limited as long as it is a fiber made of the above-mentioned biodegradable thermoplastic resin. , Short fibers or slit yarns, which can be appropriately selected. The single-fiber fineness of the biodegradable resin fiber is not particularly limited and may be appropriately selected within a range that does not impair the purpose of the present invention, but is preferably 1 to 56 dtex, and more preferably about 5 to 10 dtex. preferable. When used as a weed prevention sheet, the biodegradable resin fiber may be colored for the purpose of improving the light shielding property in order to enhance the weed prevention effect.

The woven fabric composed of biodegradable resin fibers (hereinafter sometimes abbreviated as biodegradable resin woven fabric) includes a yarn composed of the above biodegradable resin fibers, for example, a woven fabric composed of a multifilament yarn or a spun yarn. It is. The fineness of the yarn at this time may be appropriately selected within a range that does not impair the object of the present invention, but is preferably 110 to 1100 dtex, and more preferably 280 to 830 dtex. The tissue structure of the biodegradable resin fabric is not particularly limited, but a plain fabric is preferred because of its excellent properties and productivity. Also, the basis weight of the biodegradable resin fabric may be appropriately adjusted according to the properties required for the grass sheet, for example, light-shielding properties, strength, decomposition rate when biodegraded,
Usually, 100 to 250 g / m ² is preferred.

In the present invention, by controlling the cover factor of the biodegradable resin fabric to a specific range, the fabric is provided with the weed control effect, water permeability and air permeability required for the weed control sheet of the present invention. is there. That is, as the cover factor of the biodegradable resin fabric in the present invention, the cover factor (K) represented by the following formula (1) is 1000 to 1000.
2000, 1100-1800
Is preferred.

[0013]

(Equation 3) Where D _p : warp fineness (decitex) D _f : weft fineness (decitex) N _p : warp weave density (book / 2.54 cm) N _f : weft weave density (book / 2.54 cm) ρ _p : warp specific gravity (g / cm) ³ ) ρ _f : Specific gravity of weft (g / cm ³ )

When the cover factor (K) is less than 1000, the undergrowth effect is insufficient because undergrowths grow from the gaps of the fabric. On the other hand, if the cover factor (K) is 20
If it exceeds 00, water permeability and air permeability may be insufficient, which may adversely affect seedlings and seeds of plants to be originally bred. The water permeability of the woven fabric is determined according to JIS-A1218.
The water permeability measured at a water temperature of 20 ° C. and a cross-sectional area of a water-permeable cylinder of 3.14 cm ² is 1 based on the low water permeability test described in 1.
It is preferably from × 10 ^-1 to 1 × 10 ^-3 (cm / sec).

The herbicidal sheet of the present invention is a herbicidal sheet using the biodegradable resin woven fabric having the above-specified cover factor, so that it has only an excellent herbicidal effect, water permeability and air permeability. Not only, but also in strength. The tensile strength of the biodegradable resin fabric is preferably 250 N / 3 cm or more, more preferably 500 N / 3 cm.
It is more than width. If the tensile strength is less than 250 N / 3 cm width, the strength may be insufficient to hinder the laying work, or the fixing force for fixing the sheet with nails or piles may be insufficient, which is not preferable. Further, in addition to having strength, it is excellent in drape property peculiar to a woven fabric, so that workability when laying a sheet is also good. In the present invention, a colored biodegradable resin may be applied to the biodegradable resin fabric for the purpose of improving light-shielding properties, as long as the water permeability and air permeability of the herbaceous sheet are not impaired.

When the weed control sheet of the present invention is used, it is laid on the ground surface or the slope where the weeds are to be prevented from growing,
What is necessary is just to fix with a natural stone or a heavy stone, or to drive in and fix a linear or U-shaped nail. In addition, as shown in FIG. 1, a method of fixing using wooden or biodegradable resin-made piles can also be adopted. In this case, a pile 3
It is preferable to appropriately form a hole 2 for driving the sheet, and furthermore, a place to be piled is marked on a surface on which the grass sheet is laid so as to fit this hole, and then the laying and pile By performing the beating, it is possible to efficiently and beautifully construct.

In a preferred embodiment of the weed control sheet of the present invention, when planting using the weed control sheet, a hole for passing a seedling or a bud of a plant to be bred (hereinafter referred to as a plant passage hole). (May be abbreviated as). When using the grass sheet of the preferred embodiment having the plant passage hole, for example, as shown in FIG. 2, after laying and fixing the grass sheet 4, the sheet on the ground corresponding to the plant passage hole 5, that is, the sheet is used. Seeds may be sown on the exposed ground without being covered. Also, for example, as shown in FIG. 3, by aligning the position of the plant passage hole 5 with the position of the seedling 6 on the ground where the seedling has been planted in advance,
The weed control sheet 4 can be laid and used so that the seedlings 6 pass through the plant passage hole 5. The shape and size of the plant passage hole or the number thereof may be appropriately set according to the interval at which seedlings are planted or seeds are sown, or the type and quantity of plants to be planted.

[0018]

Next, the present invention will be described specifically with reference to examples. The properties of the polylactic acid and the fabric were measured by the following methods. (A) Melting point (° C.): Using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer, the rate of temperature rise was measured at 20 ° C./min, and the temperature at which an extreme value was obtained in the obtained melting endothermic curve was determined. Melting point. (B) Melt flow rate (MFR value): ASTM-D
According to the prescription of 1238 (L), the temperature is 210 ° C., the load is 21
Measured at 60 g. (C) Tensile strength Measured based on the method A (strip method) described in JIS-L1096. (D) Permeability Coefficient Based on the low water permeability test described in JIS-A1218, the water permeability was measured at a water temperature of 20 ° C. and a cross-sectional area of a water-permeable cylinder of 3.14 cm ² .

Example 1 A copolymer of poly-D-lactic acid and poly-L-lactic acid (D / L
= 1.1 / 98.9) (melting point 170 ° C,
Using a multifilament yarn (560 dtex / 96 filaments) obtained by melt-spinning an MFR value of 26 g / 10 min), a design with a warp weave density of 36 yarns / 2.54 cm and a weft weave density of 36 yarns / 2.54 cm Weaved with a basis weight of 1
A plain fabric of 65 g / m ² was obtained. The cover factor (K) of this woven fabric was 1341. 50cm of the above fabric
× 50cm and cut at one place in the center
The herbicidal sheet of the present invention having a plant passage hole was obtained by forming a circular hole having a diameter of 10 cm using a punching blade.

Example 2 The woven fabric woven in Example 1 was obtained from Dystar Japan Co., Ltd.
ianix Tuxedo Black H conc. Except for dyeing at a concentration of 10%, the same procedure as in Example 1 was carried out to obtain a herbicidal sheet of the present invention which had a plant passage hole and was colored black.

Comparative Example 1 A multifilament yarn (1
Using 100 decitex / 96 filaments), weaving is performed with a design having a warp weave density of 20 threads / 2.54 cm and a weft weave density of 20.5 threads / 2.54 cm to obtain a woven fabric having a basis weight of 180 g / m ^2. Was. The cover factor (K) of this woven fabric was 973. This woven fabric was cut in the same manner as in Example 1, and a plant passage hole was formed to obtain a weed control sheet for comparison.

Comparative Example 2 Multifilament yarn (470) made of high-strength nylon
Using decitex / 48 filaments), the warp weave density is 54 yarns / 2.54 cm and the weft weave density is 53 yarns / 2.54 cm.
cm, and a plain fabric having a basis weight of 205 g / m ² was obtained. The cover factor (K) of this woven fabric was 2035. Using this woven fabric, it was cut in the same manner as in Example 1 to form a plant passage hole, to obtain a comparative weed control sheet.

The properties of the woven fabrics used in the above-mentioned Examples and Comparative Examples are shown in Table 1 below.

[0024]

【table 1】

Further, as shown in FIG. 3, the weed control sheets of the above Examples and Comparative Examples were laid on the ground where the cedar seedlings were planted,
Table 2 below shows the results of the planting test with the fixing. The evaluation in the planting test was visually performed according to the following criteria. (A) Weed control effect ◎: Extremely excellent weed control effect. ：: There was a sufficient weed control effect. X: There was no sufficient weed control effect. (B) Seedling growth ◎: Seedlings grew extremely well. ：: The seedling grew smoothly. Δ: Seedling growth was slow. ×: Seedlings did not grow. (C) Biodegradability ：: Not degraded for 1 to 2 years, and almost completely biodegraded after 3 years. ×: Decomposed completely without decomposing even after 3 years.

[0026]

[Table 2]

As is evident from the above results, the herbicidal sheet of the present invention has a sufficient herbicidal effect and has a suitable water permeability and air permeability, so that it does not hinder the growth of seedlings. Rather, the prevention of undergrowth was a good result for seedling growth. In addition, almost complete biodegradation eliminated the need for recovery. On the other hand, in the case of Comparative Example 1, the cover factor was 973 and the gap between the woven fabrics was large, and the seedlings were rich in water permeability and air permeability, but the seedlings grew for a while, but the undergrowth grew more than that. It had no herbicidal effect, and as a result, the growth of seedlings was slow. In addition, in the case of Comparative Example 2, the cover factor was too large, so that the water permeability and the air permeability were insufficient, and although there was a herbicidal effect, the growth of the seedlings to be originally raised was hindered. Furthermore, since the sheets of Comparative Examples 1 and 2 were non-degradable,
The recovery process also took time.

[0028]

The weed control sheet of the present invention has an excellent weed control effect, so that when used for planting, there is no need to cut down undergrowth with human hands, and the plant that should be planted is surely used. Can be grown. When the planted seedlings and seeds grow and become self-sustaining (two to three years), the biodegradable resin fibers are decomposed into harmless substances such as carbon dioxide and water by biodegradation, and the sheet remains. Since it is no longer necessary, there is no need to perform a recovery process, and there is no pollution of the natural environment. further,
Since it has the high strength and drape characteristic of a woven fabric, it is excellent in workability during laying work, and can be suitably used not only on flat ground but also on undulating ground, slopes and slopes. Therefore, it can be used as a suitable grass-protecting sheet in various scenes requiring grass-protection, such as various types of planting and landscape maintenance purposes, and various civil engineering works.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a method for using a grass sheet of the present invention.

FIG. 2 is a perspective view showing an example of use of an embodiment of the weed prevention sheet of the present invention.

FIG. 3 is a perspective view showing an example of use of an embodiment of the weed prevention sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Weed prevention sheet 2 Hole for driving a pile 3 Pile 4 Weed prevention sheet having a plant passage hole 5 Plant passage hole 6 Seedling

Claims (2)

[Claims] 1. A weed prevention sheet using a woven fabric made of biodegradable thermoplastic resin fibers, wherein the woven fabric has a cover factor (K) represented by the following formula (1) of 100:
A weed-proofing sheet characterized by being from 0 to 2,000. (Equation 1) Where D _p : warp fineness (decitex) D _f : weft fineness (decitex) N _p : warp weave density (book / 2.54 cm) N _f : weft weave density (book / 2.54 cm) ρ _p : warp specific gravity (g / cm) ³ ) ρ _f : Specific gravity of weft (g / cm ³ ) 2. The herbicidal sheet according to claim 1, further comprising a hole through which a seedling or a bud of a plant to be grown passes.