JP3905210B2

JP3905210B2 - Biodegradable solid network structure

Info

Publication number: JP3905210B2
Application number: JP07129798A
Authority: JP
Inventors: 宏谷内; 健二地本
Original assignee: Daiwabo Co Ltd; Daiwabo Holdings Co Ltd
Current assignee: Daiwabo Co Ltd; Daiwabo Holdings Co Ltd
Priority date: 1998-03-04
Filing date: 1998-03-04
Publication date: 2007-04-18
Anticipated expiration: 2018-03-04
Also published as: JPH11247060A

Description

【０００１】
【発明の属する技術分野】
本発明は、植生用の土木資材、海藻生育用の海洋資材等に用いられる立体網状構造物に関する。
【０００２】
【従来の技術】
従来の植生用の土木資材や海藻生育用の海洋資材に用いられている立体網状構造物は、例えば実開昭６０−１４１３６号公報や特開平９−１２１７０２号公報の記載にみられるように、微生物によって分解しないポリオレフィン系熱可塑性樹脂が用いられている。そのため、植生または海藻生育後においてもその形態を保持するため、使用後の回収の際には多大な労力と経費を必要とし、また、回収後の処理についても焼却等により処理されているが、その消費量が増大するに従い処理が間に合わず大きな問題となっている。
【０００３】
【発明が解決しようとする課題】
本発明は、前記従来技術の問題点を解決するために、一定期間使用後は自然環境になじんだもの、すなわち、土木資材あるいは海洋資材のための施工作業を容易に行うことが出来、且つ使用後は微生物によって自然分解されることにより、回収不要の立体網状構造物を提供しようとするものである。
【０００４】
【課題を解決するための手段】
本発明は、直径０．１〜２．０ｍｍの多数の合成重合体連続線条の各々が不規則なループをなして相互に交差し、かつ厚み方向に湾曲して一方から他方に延び、その多数の合成重合体連続線条がそれぞれの交差点において相互に接着され、表面には多数の畝状の山部とその山部間において窪んだ溝状の谷部が形成され、この山部および谷部は裏面において谷部および山部を形成して、見掛け厚さが１０〜１００ｍｍであって、空隙率５０〜９９％、平行光線透過率１０〜７０％の嵩高な網状部によってマット面が形成される立体網状マットからなり、該合成重合体連続線条が、微生物によって分解可能な熱可塑性樹脂を主体としてなることを特徴とした生分解性立体網状構造物であり、微生物によって分解可能な熱可塑性樹脂が、融点（Ｔｍ℃）が５０＜Ｔｍ＜１７０の温度範囲にある脂肪族ポリエステル樹脂よりなることを特徴としたものである。以下に本発明について詳細に説明する。
【０００５】
本発明に用いる微生物によって分解可能な熱可塑性樹脂は、例えば脂肪族ポリエステル樹脂が好ましく用いられる。脂肪族ポリエステル樹脂には脂肪族の２価カルボン酸を含む多価カルボン酸と脂肪族系ジオールを含む多価アルコールとの重縮合物、ヒドロキシ脂肪族カルボン酸の重縮合物、ラクトンの開環重合物が包含される。これらは例えばエチレンジアジペート、プロピオラクトン、β−ヒドロキシ酪酸等から誘導される単独重合体や共重合体がある。脂肪族ポリエステルに低分子量のポリアミドをブロック重合させたものも用いれる。これらの内から融点（Ｔｍ℃）が９０＜Ｔｍ＜１７０の微生物によって生産された脂肪族ポリエステル、または、５０＜Ｔｍの人工的に合成された脂肪族ポリエステルを選択して使用する。また、１００＜Ｔｍ＜１６０の変性澱粉と変性ポリビニルアルコールからなるポリマーアロイ、熱可塑性の変性リグニンなど動植物由来の熱可塑性樹脂も用いることができる。
【０００６】
また、微生物による生分解を促進、調整するために、前記微生物によって分解可能な熱可塑性樹脂にセルロース系パウダー状物や、蛋白質、澱粉、乳糖、脂肪、半繊維分解酵素を含んだ微生物活性剤等を添加させてもよい。
【０００７】
また、本発明による生分解性立体網状構造物が、直径０．１〜２．０ｍｍの多数の合成重合体連続線条の各々が不規則なループをなして相互に交差し、かつ厚み方向に湾曲して一方から他方に延び、その多数の合成重合体連続線条がそれぞれの交差点において相互に接着され、表面には多数の畝状の山部とその山部間において窪んだ溝状の谷部が形成され、この山部および谷部は裏面において谷部および山部を形成して、見掛け厚さが１０〜１００ｍｍであって、空隙率５０〜９９％、平行光線透過率１０〜７０％の嵩高な網状部によってマット面が形成される立体網状構造物からなることが望ましい。立体網状構造物であるため、シート状物と比較し、植生用の土木資材、海藻生育用の海洋資材等に適した形態を有することになる。また連続線条により立体的に山部および谷部が形成されているため、土中、水中においてより生分解しやすい利点を有することになる。また、連続線条の直径、密度を調整することにより生分解期間の調整も可能である。連続線条の直径は、０．１ｍｍ未満では線状が細過ぎて立体網状構造物全体の強力が不十分となり、２．０ｍｍを越えると剛性が大きくなり、立体網状構造物の表面に山部と谷部が形成されにくくなるので好ましくない。この立体網状構造物は、例えば図１に示すような装置を用いて製造することが出来る。この装置は、孔径０．１〜２．０ｍｍの紡糸孔が６〜２０ｍｍ間隔で窄設された紡糸孔列が平行に、もしくは、紡糸孔が交互に位置するような千鳥状に２〜３列に亙って設けられた紡糸口金１１と、口金の下方に配置され、表面に山部３と谷部４を有する搬送体１２で構成されている。立体網状構造物を製造するときは、原料となる合成重合体を溶融状態で紡糸口金から連続線条２として紡糸し、連続線条２の落下速度よりも遅い速度で矢印方向に移動している搬送体１２の上に自然落下させ、不規則なループを描かせて隣接する連続線条２と交差させながら順次積層させる。そして、その集積時に連続線条を相互にそれぞれの交差点において自己融着させた後、冷却すれば搬送体の山部３と谷部４に対応して山部、谷部が形成された立体網状構造物１を得ることが出来る。
【０００８】
この時、連続線条が太すぎると線条が垂下しにくくなり、搬送体の谷部に対応させることができなくなるため、連続線条の直径は前述した範囲内にすることが望ましい。また、紡糸口金を複数個設ければ、種類の異なる線条を紡糸することができ、複数種の連続線条で構成された立体網状構造物を得ることができる。このようにして得られる立体網状構造物においては、溝状の谷部が形成されているため土木資材としての植生用で植物の根、茎は谷部に沿って這う事ができ、生育が阻害されることはない。又、海洋資材としての海藻生育基盤材で、アマモのような海藻であっても茎は谷部に沿って這うことができ生育が阻害されることはない。
【０００９】
最終的に得られる立体網状構造物の空隙率５０〜９９％、平行光線透過率１０〜７０％であることが望ましい。空隙率５０％未満、平行光線透過率１０％未満では、連続線条の間に形成される隙間が小さくなり、例えばアマモのように砂地に根を下ろす海藻の場合、根の通り抜けが困難になるからである。また、空隙率９９％越え、平行光線透過率７０％越となると、立体網状構造物の強度が弱くなり耐久性の面で問題が生じる。また、立体網状構造物の見掛けの厚みは１０〜１００ｍｍであることが望ましい。ここで見掛けの厚みとは、立体網状構造物を剛性のある平板の上に置き、さらに、構造物の上に軽くて剛性のある平板を置いた時の、平板と平板の間の距離をいう。１０ｍｍ未満では山部と谷部の高低差が小さくなり、表面が平坦化するため好ましくない。厚みが１００ｍｍ越えの立体網状構造物は製造が困難でコストの上昇につながるために実用的でない。
【００１０】
【発明の実施の形態】
発明の実施の形態を実施例にもとずき図面を参照しながら説明すると、図１は本発明の生分解性立体網状構造物の製造装置の一例を略示した側面図である。図２は本発明の生分解性立体網状構造物の一部を示した斜視図である。図３は本発明の生分解性立体網状構造物の山部と谷部を平面的に表した説明図である。図において、１は立体網状構造物、２は連続線条、３は山部、４は谷部、である。
【００１１】
【実施例】以下に実施例で本発明について詳細に説明する。尚、実施例中の評価は以下の方法で測定した。
「厚み」１０ｃｍ角のサンプルを５枚作成し各サンプル中央部に３ｇ／ｃｍ2 荷重をかけ厚みを測定、各測定値を平均して算出した。
「空隙率」連続線条正味体積を見掛け体積で除した値を１より引いた値に１００を乗じ算出した。
「平行光線透過率」網状体の平面の一部を切り取り、これを裏面から平行光線を照射できるガラス盤上に置きガラス盤に垂直に設置したＣＣＤカメラより画像を取り込み電算機により明暗を２値化し明部分の面積を処理画像面積で除して算出した。
【００１２】
（実施例１）立体網状構造物を製造すべく、前記図１のような装置を使用し、直径１ｍｍの紡糸孔が１０ｍｍ間隔で窄設されている紡糸孔列が二列に亙って平行に設けられている紡糸口金１１を用意し、又、搬送体１２として図３のように山部３と谷部４が設けられたものを用意した。そして、搬送体１２と紡糸口金１１の間隔は約２０ｃｍ、搬送体１２の移動速度は２ｍ／分に設定した。原料として、昭和高分子社製生分解性樹脂「ビオノーレ」（登録商標）＃１０１０（融点１１４℃）を用意し、これを溶融状態で紡糸口金から紡出させ、連続線条２の落下速度よりも遅い速度で矢印方向に移動している搬送体１２の上に自然落下させ、不規則なループを描かせて隣接する連続線条２と交差させながら順次集積して連続線条２群が搬送体１２の表面形状に沿って山部と谷部を形成するようにし、集積時に連続線条を相互にそれぞれの交差点において自己融着させた。そして、冷却し表面に山部３と谷部４を有する図２のような生分解性立体網状構造物１を得た。
【００１３】
得られた生分解性立体網状構造物１は、直径約０．８ｍｍの多数の連続線条の各々が不規則なループをなして相互に交差し、かつ厚み方向に湾曲して一方から他方に延び、その多数の連続線条がそれぞれ交差点において相互に接着されてなる目付が約１１００ｇ／ｍ²、見掛けの厚みが２６ｍｍの嵩高な網状物で構成され、マット面の円弧状をなした山部の幅は約２０ｍｍ、山部間隔は約２５ｍｍであって、マット面の網状部における空隙率が９７％、平行光線透過率が４６％であった。また、引っ張り強力７Ｋｇ／５ｃｍおよび伸び率４０％の値を示し、充分実用に耐えられるものであった（ＪＩＳ１０９６に準じて測定）。
【００１４】
（比較例１）使用樹脂として、オレフィン系樹脂のプロピレン−エチレン−ブテンの三元共重合物を使用した以外は実施例１と同様な製造方法にて立体網状構造物２を得た。
【００１５】
得られた立体網状構造物２は、直径約０．８ｍｍの多数の連続線条の各々が不規則なループをなして相互に交差し、かつ厚み方向に湾曲して一方から他方に延び、その多数の連続線条がそれぞれ交差点において相互に接着されてなる目付が約１１００ｇ／ｍ²、見掛けの厚みが２８ｍｍの嵩高な網状物で構成され、マット面の円弧状をなした山部の幅は約２０ｍｍ、山部間隔は約２５ｍｍであって、マット面の網状部における空隙率が９６％、平行光線透過率が４５％であった。
【００１６】
前記実施例１と比較例１で得られた立体網状構造物を畑地の土壌中に埋め、約１２か月後に掘り起こした所、比較例１で得られた立体網状構造物は原形を保っていたが、本発明による実施例１で得られた立体網状構造物は、原形をとどめずバラバラの状態であった。
【００１７】
【発明の効果】
本発明による生分解性立体網状構造物は、微生物によって分解可能な熱可塑性樹脂を主体にしてなるため、一定期間使用後は、生分解されて最終的に炭酸ガスと水になり、環境を汚すことはない。よって、使用後の余分な回収の労力およびそれに必要な経費を節約することができる。また、たとえ焼却されても燃焼カロリーがポリエチレンの約半分で焼却炉を損傷しにくい。
【図面の簡単な説明】
【図１】本発明の生分解性立体網状構造物の製造装置の一例を略示した側面図である。
【図２】本発明の生分解性立体網状構造物の一部を示した斜視図である。
【図３】本発明の生分解性立体網状構造物の山部と谷部を平面的に表した説明図である。
【符号の説明】
１立体網状構造物
２連続線条
３山部
４谷部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional network structure used for civil engineering materials for vegetation, marine materials for seaweed growth, and the like.
[0002]
[Prior art]
The three-dimensional network structure used for civil engineering materials for conventional vegetation and marine materials for seaweed growth is, for example, as described in Japanese Utility Model Laid-Open No. 60-14136 and JP-A-9-121702. Polyolefin thermoplastic resins that are not degraded by microorganisms are used. Therefore, in order to maintain the form even after vegetation or seaweed growth, a great deal of labor and expense is required for the recovery after use, and the processing after recovery is processed by incineration etc. As the amount of consumption increases, processing is not in time, which is a big problem.
[0003]
[Problems to be solved by the invention]
In order to solve the problems of the prior art, the present invention can easily perform construction work for a natural environment after use for a certain period, that is, a civil engineering material or a marine material. After that, it is intended to provide a three-dimensional network structure that does not need to be recovered by being naturally decomposed by microorganisms.
[0004]
[Means for Solving the Problems]
In the present invention, each of a large number of synthetic polymer continuous filaments having a diameter of 0.1 to 2.0 mm intersects each other in an irregular loop, and is curved in the thickness direction to extend from one to the other. A large number of synthetic polymer continuous filaments are bonded to each other at their respective intersections, and a large number of bowl-shaped peaks and groove-shaped valleys that are recessed between the peaks are formed on the surface. The part forms valleys and ridges on the back surface, the apparent thickness is 10 to 100 mm, and the matte surface is formed by a bulky net-like part having a porosity of 50 to 99% and a parallel light transmittance of 10 to 70% A biodegradable three-dimensional network structure characterized in that the synthetic polymer continuous filament is mainly composed of a thermoplastic resin decomposable by microorganisms, and is a heat decomposable by microorganisms. The plastic resin has a melting point (Tm ) Is one that was characterized by consisting of an aliphatic polyester resin in the temperature range of 50 <Tm <170. The present invention is described in detail below.
[0005]
As the thermoplastic resin that can be decomposed by the microorganisms used in the present invention, for example, an aliphatic polyester resin is preferably used. Aliphatic polyester resins include polycondensates of polycarboxylic acids containing aliphatic divalent carboxylic acids and polyhydric alcohols containing aliphatic diols, polycondensates of hydroxyaliphatic carboxylic acids, and ring-opening polymerization of lactones. Things are included. These include, for example, homopolymers and copolymers derived from ethylene diadipate, propiolactone, β-hydroxybutyric acid and the like. A material obtained by block polymerizing a low molecular weight polyamide to an aliphatic polyester is also used. Among these, an aliphatic polyester produced by a microorganism having a melting point (Tm ° C.) of 90 <Tm <170 or an artificially synthesized aliphatic polyester of 50 <Tm is selected and used. Further, a thermoplastic resin derived from animals and plants such as a polymer alloy composed of a modified starch of 100 <Tm <160 and a modified polyvinyl alcohol, and a thermoplastic modified lignin can also be used.
[0006]
In addition, in order to promote and adjust biodegradation by microorganisms, microbial activators containing cellulose-based powders, proteins, starch, lactose, fats, and half-fiber degrading enzymes in thermoplastic resins that can be degraded by microorganisms, etc. May be added.
[0007]
In addition, the biodegradable three-dimensional network structure according to the present invention is such that each of a large number of synthetic polymer continuous filaments having a diameter of 0.1 to 2.0 mm intersects each other in an irregular loop, and in the thickness direction. Curved and extended from one to the other, a number of synthetic polymer continuous filaments are bonded to each other at each intersection, and the surface has a number of bowl-shaped peaks and groove-shaped valleys that are recessed between the peaks. The crests and troughs form troughs and crests on the back surface, the apparent thickness is 10 to 100 mm, the porosity is 50 to 99%, and the parallel light transmittance is 10 to 70%. It is desirable to be made of a three-dimensional network structure in which a mat surface is formed by a bulky network part. Since it is a three-dimensional network structure, it has a form suitable for civil engineering materials for vegetation, marine materials for seaweed growth, and the like as compared with sheet-like materials. In addition, since the crest and trough are three-dimensionally formed by the continuous filaments, there is an advantage that biodegradation is easier in soil and water. In addition, the biodegradation period can be adjusted by adjusting the diameter and density of the continuous filaments. If the diameter of the continuous filament is less than 0.1 mm, the linear shape is too thin and the strength of the entire three-dimensional network structure is insufficient, and if it exceeds 2.0 mm, the rigidity is increased, and a peak is formed on the surface of the three-dimensional network structure. Since it is difficult to form valleys, it is not preferable. This three-dimensional network structure can be manufactured using, for example, an apparatus as shown in FIG. This apparatus has two or three rows in a staggered manner in which spinning hole rows in which spinning holes having a hole diameter of 0.1 to 2.0 mm are narrowed at intervals of 6 to 20 mm are arranged in parallel or alternately. The spinneret 11 is provided over the base, and the carrier 12 is disposed below the base and has a crest 3 and a trough 4 on the surface. When producing a three-dimensional network structure, a synthetic polymer as a raw material is spun from a spinneret as a continuous filament 2 in a molten state, and moved in the direction of the arrow at a speed slower than the falling speed of the continuous filament 2 It is allowed to naturally fall on the carrier 12, and an irregular loop is drawn and laminated successively while intersecting with the adjacent continuous filaments 2. Then, after the continuous filaments are self-fused to each other at the respective intersections at the time of accumulation, and then cooled, a three-dimensional network shape in which peaks and valleys are formed corresponding to the peaks 3 and valleys 4 of the carrier The structure 1 can be obtained.
[0008]
At this time, if the continuous filament is too thick, it becomes difficult for the filament to hang down, and it becomes impossible to correspond to the valley portion of the carrier. Therefore, the diameter of the continuous filament is preferably within the above-described range. If a plurality of spinnerets are provided, different types of filaments can be spun and a three-dimensional network structure composed of a plurality of types of continuous filaments can be obtained. In the three-dimensional network structure obtained in this way, since the groove-shaped valley is formed, the roots and stems of plants can be planted along the valley for vegetation as civil engineering materials, and the growth is inhibited. It will never be done. Moreover, even if it is a seaweed growth base material as a marine material, even if it is a seaweed like an amamo, a stem can crawl along a trough part and growth will not be inhibited.
[0009]
It is desirable that the finally obtained three-dimensional network structure has a porosity of 50 to 99% and a parallel light transmittance of 10 to 70%. When the porosity is less than 50% and the parallel light transmittance is less than 10%, the gap formed between the continuous filaments becomes small. For example, in the case of a seaweed that roots in sand like an amamo, it is difficult to pass through the root. Because. On the other hand, if the void ratio exceeds 99% and the parallel light transmittance exceeds 70%, the strength of the three-dimensional network structure becomes weak, causing a problem in terms of durability. The apparent thickness of the three-dimensional network structure is preferably 10 to 100 mm. Here, the apparent thickness refers to the distance between a flat plate when a three-dimensional network structure is placed on a rigid flat plate and a light and rigid flat plate is placed on the structure. . If it is less than 10 mm, the height difference between the peak and the valley becomes small and the surface becomes flat, which is not preferable. A three-dimensional network structure having a thickness exceeding 100 mm is not practical because it is difficult to manufacture and leads to an increase in cost.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the invention will be described with reference to the drawings based on examples. FIG. 1 is a side view schematically showing an example of a biodegradable three-dimensional network manufacturing apparatus according to the present invention. FIG. 2 is a perspective view showing a part of the biodegradable three-dimensional network structure of the present invention. FIG. 3 is an explanatory view showing the peaks and valleys of the biodegradable three-dimensional network structure of the present invention in a plan view. In the figure, 1 is a three-dimensional network structure, 2 is a continuous filament, 3 is a peak, and 4 is a valley.
[0011]
The present invention will be described in detail with reference to the following examples. The evaluation in the examples was measured by the following method.
“Thickness” Five 10 cm square samples were prepared, a thickness of 3 g / cm 2 was applied to the center of each sample, the thickness was measured, and each measured value was averaged.
“Porosity” The value obtained by subtracting the value obtained by dividing the continuous linear net volume by the apparent volume from 1 was calculated by multiplying by 100.
“Parallel light transmittance” A part of the plane of the reticulate body is cut out, and this is placed on a glass plate that can be irradiated with parallel light from the back side, and the image is taken in from a CCD camera installed vertically on the glass plate. Calculated by dividing the area of the bright part by the area of the processed image.
[0012]
(Example 1) In order to manufacture a three-dimensional network structure, the apparatus shown in Fig. 1 is used, and spinning hole rows in which spinning holes having a diameter of 1 mm are constricted at intervals of 10 mm are parallel in two rows. A spinneret 11 provided in the above-mentioned structure was prepared, and a carrier 12 having a crest 3 and a trough 4 as shown in FIG. 3 was prepared. And the space | interval of the conveyance body 12 and the spinneret 11 was set to about 20 cm, and the moving speed of the conveyance body 12 was set to 2 m / min. As a raw material, biodegradable resin “Bionore” (registered trademark) # 1010 (melting point: 114 ° C.) manufactured by Showa Polymer Co., Ltd. was prepared and spun from a spinneret in a molten state. It is naturally dropped onto the carrier 12 moving in the direction of the arrow at a slow speed, and an irregular loop is drawn to sequentially accumulate while intersecting the adjacent continuous filaments 2 to convey the continuous filaments 2 group. Crests and troughs were formed along the surface shape of the body 12, and the continuous filaments were self-fused at each intersection at the time of integration. And it cooled and the biodegradable solid network structure 1 like FIG. 2 which has the peak part 3 and the trough part 4 on the surface was obtained.
[0013]
In the obtained biodegradable three-dimensional network structure 1, each of a large number of continuous filaments having a diameter of about 0.8 mm intersects each other in an irregular loop, and curves in the thickness direction from one to the other. A ridge that is formed by a bulky net having a weight per unit area of about 1100 g / m ² and an apparent thickness of 26 mm. The width of each was about 20 mm, the interval between the crests was about 25 mm, the porosity in the mesh portion of the mat surface was 97%, and the parallel light transmittance was 46%. Moreover, the tensile strength was 7 kg / 5 cm and the elongation was 40%, which was sufficient for practical use (measured according to JIS1096).
[0014]
(Comparative example 1) The three-dimensional network structure 2 was obtained with the manufacturing method similar to Example 1 except having used the ternary copolymer of propylene-ethylene-butene of olefin resin as resin to be used.
[0015]
In the obtained three-dimensional network structure 2, each of a large number of continuous filaments having a diameter of about 0.8 mm intersects each other in an irregular loop, and is curved in the thickness direction to extend from one to the other. A large number of continuous filaments are bonded to each other at the intersection, the basis weight is about 1100 g / m ² , the apparent thickness is 28 mm, and the mat portion has an arcuate peak width. About 20 mm, the crest spacing was about 25 mm, the porosity in the mesh portion of the mat surface was 96%, and the parallel light transmittance was 45%.
[0016]
The solid network structure obtained in Example 1 and Comparative Example 1 was buried in upland soil and dug up about 12 months later. The solid network structure obtained in Comparative Example 1 kept its original shape. However, the three-dimensional network structure obtained in Example 1 according to the present invention did not stay in its original form and was in a disassembled state.
[0017]
【The invention's effect】
The biodegradable three-dimensional network structure according to the present invention is mainly composed of a thermoplastic resin that can be decomposed by microorganisms. Therefore, after use for a certain period of time, it is biodegraded and finally becomes carbon dioxide and water, which pollutes the environment. There is nothing. Therefore, it is possible to save extra recovery effort after use and necessary expenses. Moreover, even if incinerated, the calorie burned is about half that of polyethylene, making it difficult to damage the incinerator.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing an example of a production apparatus for a biodegradable three-dimensional network structure according to the present invention.
FIG. 2 is a perspective view showing a part of the biodegradable three-dimensional network structure of the present invention.
FIG. 3 is an explanatory view showing the peaks and valleys of the biodegradable three-dimensional network structure of the present invention in a plan view.
[Explanation of symbols]
1 Three-dimensional network structure 2 Continuous filament 3 Mountain part 4 Valley part

Claims

Each of a large number of synthetic polymer continuous filaments having a diameter of 0.1 to 2.0 mm intersects each other in an irregular loop, and is curved in the thickness direction to extend from one to the other. Combined continuous filaments are bonded to each other at each intersection, and a number of ridge-like ridges and groove-like valleys for plant growth recessed between the ridges are formed on the surface. Forms a trough and a crest on the back surface, has an apparent thickness of 10 to 100 mm, and a matte surface is formed by a bulky mesh portion having a porosity of 50 to 99% and a parallel light transmittance of 10 to 70%. The synthetic polymer continuous filament is a polycondensate of a polyvalent carboxylic acid containing an aliphatic divalent carboxylic acid decomposable by microorganisms and a polyhydric alcohol containing an aliphatic diol. A certain aliphatic polyester resin Plant growth for biodegradable three-dimensional net-like structure which is characterized by comprising a.

The biodegradable three-dimensional network structure for plant growth according to claim 1, wherein the melting point (Tm ° C) of the aliphatic polyester resin is in a temperature range of 50 <Tm <170.