JP2002335780A - Mulching film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mulching film, capable of surely carrying out cutting treatment of the film at the boundary between a part of the film buried in soil and a part of the film not buried in soil when recovered from a field, capable of reducing labor of workers therefor and readily carrying out reutilization and disposal treatment of recovered mulching film. SOLUTION: This mulching film is characterized by dividing the film into three parts consisting of a central part and two side parts interposing the central part, parallel in the longitudinal direction, wherein the central part has no biodegradability and two side parts have biodegradability or the mulching film is characterized by dividing the film into three parts consisting of the central part and two side parts interposing the central part, parallel in the longitudinal direction, wherein all of the central part and the side parts have biodegradability and degrading speed of the central part is slower in soil than the degrading speeds of the side parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-film which is used by spreading it on a ridge or the like in order to improve the cultivation efficiency of crops.

[0002]

2. Description of the Related Art Conventionally, various polyethylene multi-films have been proposed in order to improve the cultivation efficiency of agricultural products. For example, a transparent multi-film that prevents the soil temperature of the ridge from being lowered by the outside air, a silver or milky-colored multi-film that reflects the sunlight and suppresses the rise of the soil temperature, and a weed that absorbs the sunlight and absorbs sunlight There are black multi-films that prevent the overgrowth. Since these multi-films do not have biodegradability and do not decompose even after long-term use, it is necessary to collect and discard the multi-film after harvesting the crop. However, the recovery is very hard work,
If part of the multi-film could not be collected during collection and could not be collected, the collected and left over film would be left in the natural world, destroying the environment. . In addition, the problem of multi-film disposal has become a serious social problem in recent years following the prohibition of open burning, and drastic measures have been required.

Therefore, various agricultural films made of a biodegradable polymer material have been studied. For example, Japanese Patent Publication No. 51-48975 discloses that a linear higher fatty acid linear higher alcohol ester is added to a polyolefin and nitrogen,
A biodegradable agricultural film characterized by being formed by blending an inorganic or organic compound of phosphorus or potassium is disclosed. JP-B-59-8365 discloses an ester-amide exchange product obtained by heating and melting a mixture of a high-molecular-weight polycaprolactone and a high-molecular-weight aliphatic polyamide until a clear melting point drop is observed at a temperature higher than their melting points. BACKGROUND ART A biodegradable agricultural multi-film formed from a material is disclosed. Furthermore, Japanese Patent Application Laid-Open Nos. 3-259935 and 3-263441 are disclosed.
Publication No. 1 discloses an ethylene-vinyl alcohol copolymer 10
A multi-cultivation film for agriculture comprising a composition containing -90% by weight and 90-10% by weight of starch as a main component is disclosed.

By the way, when a crop is cultivated using a biodegradable multi-film and then the multi-film is collected from the ridge, biodegradation of the portion of the multi-film buried in the soil is not buried in the soil. Because it is more advanced than that of the part, it is usually cut along the border of both parts, but depending on the usage period of the multi-film, it is not cut at this border, and the part buried in the soil is involved In some cases, it was recovered. The portion buried in the soil has a large amount of soil attached thereto, which has troubled the operator in the film collection work. In addition, it is inconvenient to reuse the collected multi-film, and it is also inconvenient to dispose of the film by incineration or the like because of its increased weight.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances. In other words, after cultivating the crop using the multi-film, when collecting the multi-film from the ridge, when the multi-film is buried in the soil, the multi-film surely at the boundary of the portion that was not buried in the soil It is an object of the present invention to provide a multi-film that can reduce the labor of the operator, and that can reuse the collected multi-film and facilitate disposal processing.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies. As a result, among the multi-films spread on the ridges, it has been found that the above-mentioned problem can be solved by forming the portion covered with soil from a resin having a higher biodegradation rate than the portion not covered with soil, and completed the present invention. It led to. That is, in the present invention, the film is divided into three parts in parallel with the longitudinal direction, a central part and two side parts sandwiching the central part, the central part is not biodegradable, and the side part is biodegradable. A multi-film having properties.

Further, according to the present invention, the film is divided into three parts parallel to the longitudinal direction thereof into a central portion and two sides sandwiching the central portion, and both the central portion and the side portions have biodegradability. In addition, the multi-film is characterized in that the decomposition rate in the central part is lower in the soil than in the side parts.

Further, the present invention is characterized in that a biodegradable outer layer is arranged on at least one surface of a film divided into three at a central part and two side parts sandwiching the central part. 2. The multi-film according to claim 1.

That is, the multi-film of the present invention is not divided into a single film, but is divided into three in the longitudinal direction of the film.
The central part that is not buried in the soil when using multi-film,
It has no biodegradability or has a relatively low biodegradation rate, and the side buried in the soil has a relatively high biodegradation rate. Further, the film is constituted by disposing an outer layer having biodegradability on at least one surface of the film.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The biodegradable synthetic resin used in the present invention is not limited, but may be poly-ε-caprolactone (PCL), polybutylene succinate (PBS), or polybutylene succinate. / Adibate (PBSA), polylactic acid (PLA), terephthalate-modified type of polybutylene succinate (P
BST), carbonate-modified polybutylene succinate (PEC), polyethylene succinate (
Aliphatic polyester resins such as PES) are preferred. These can be used in appropriate combination according to the target biodegradability rate. According to the study of the present inventors, the order of the biodegradation rate of these resins is as follows. PES>PCL>PBSA>PBS> PBST @ PEC
> PLA

Note that PCL is marketed, for example, by Daicel Chemical Industries, Ltd. under the trade name "Cell Green". PBS and PBSA are marketed by Showa Kogaku Co., Ltd. under the trade name "Bionore". PBST is D
"Biomax", "Eas" from uPont, Eastman Chemical and BASF respectively
terbio ”and“ Ecoflex. ”PEC is marketed by Mitsubishi Gas Chemical Co., Ltd. under the trade name“ UPEC. ”PES is marketed by Nippon Shokubai Co., Ltd. under the trade name“ Lunare SE. ” Have been.

On the other hand, the synthetic resin having no biodegradability used in the present invention is not limited, and examples thereof include polypropylene, propylene-ethylene copolymer, polybutene-1, poly4-methylpentene-1, -, Medium-,
Or polyolefins such as high density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ion-crosslinked olefin copolymer (ionomer), saponified ethylene-vinyl acetate copolymer Aromatic vinyl copolymers such as polystyrene and styrene-butadiene copolymer; polyvinyl chloride;
Vinyl halide polymers such as vinylidene chloride resin; acrylonitrile-styrene copolymer, acrylonitrile-
A nitrile polymer such as a styrene-butadiene copolymer;
Polyamides such as nylon 6, nylon 66, para- or meta-xylylene adipamide; polyesters such as polyethylene terephthalate and polytetramethylene terephthalate; various polycarbonates; and thermoplastic resins such as polyacetals such as polyoxymethylene. One or more of these can be used in combination, but polyolefins represented by low density polyethylene are most suitable. The synthetic resin may be added with various known additives to improve its weather resistance, slipperiness, and thermal stability, and various colorants such as black, white, and silver depending on the purpose. Can be added.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view (A) showing one embodiment of the multi-film 1 of the present invention, and aa ′ in (A).
(B) of FIG. The multi-film 1 of this embodiment is divided into three parts in parallel with the longitudinal direction of the film,
A portion located in the center of the film 2 is referred to as a center portion 21, and portions located on both sides are referred to as side portions 22. The side portion 22 corresponds to a portion to be covered with soil at the time of expansion, and its width is appropriately set in a range of 30 to 500 mm according to the width and height of the ridge provided in the ridge field to be used. .

FIG. 2 is a plan view (A) showing another embodiment of the multi-film of the present invention, and a cross-sectional view (B) taken along the line bb 'of (A). In the multi-film of this embodiment, an outer layer 3 having biodegradability is further laminated on both surfaces of the multi-film of the embodiment shown in FIG. Note that the outer layer may be laminated only on one surface of the multi-film of the embodiment shown in FIG.

The multi-film 1 of the present invention is divided into three parts by a central portion and two side portions sandwiching the central portion.
There is a difference in biodegradation rate between 1 and side 22. The method for providing a difference in the biodegradation rate is not particularly limited, but the following four examples are given. (1) The central part is formed from a resin having no biodegradability,
The sides are formed from a biodegradable resin. (2) The type of the biodegradable resin that is the main component is changed between the central part and the side part, and the biodegradable speed of the side part is set high. (3) An additive that promotes the decomposition of the center part and the side part using the same type of biodegradable resin as a main component,
It is called a decomposition accelerator. ) Is changed. Degradability promoters include cellulose powder, pulp powder, sander powder, straw, rice straw, palm, rice husk, waste paper, linter,
Examples thereof include crushed vegetable fibers such as bagasse, or other lignocellulosic materials containing cellulose or lignin as a main component, and inorganic powders such as calcium carbonate, diatomaceous earth, and talc that have water absorption. (4) A central part and a side part are composed of the same type of biodegradable resin as a main component, and an additive (hereinafter referred to as a “decomposition-suppressing additive”) mixed therewith
It is called a decomposition inhibitor. ) Is changed. Examples of the degradability inhibitor include synthetic resins having no biodegradability.

The decomposition accelerator described in the above (3) is
In the methods described in (1) and (2), it may be appropriately blended with the biodegradable resin constituting the side portion.

Further, in the multi-film according to the first and second aspects of the present invention, the strength of the boundary between the central portion and the side portions may be weakened. There is a risk of breaking from the border. Therefore, in order to reinforce this portion, the multi-layer film according to the present invention is formed into a multilayer, and an outer layer made of a biodegradable synthetic resin is provided on at least one of a central portion and at least one of three divided films on two sides sandwiching the central portion. Is preferably provided.

Furthermore, if the boundary portions between the central portion and the side portions of the multi-film of the present invention are known, the extent to which the soil should be covered when the film is stretched on the ridges is a guide. Therefore, the boundary may be printed so that the boundary between the center and the side can be recognized. In addition, if a colorant is added to one of the synthetic resin for molding the central portion and the synthetic resin for molding the side portions, or a colorant of another color is added to both of them, the film is formed. The operator can be notified of the boundary between the central portion and the side portion without performing processing such as printing later.

A method for producing a multi-film of the above-described embodiment will be described. The method for producing the multi-film of the present invention is not particularly limited, for example, one film consisting of only the central portion and two films consisting of only the side portions are prepared, and the side portions are located on both sides of the central portion. It is obtained by joining the sides of the central portion and the sides of the side portion by a method such as heat welding. Further, as another manufacturing method, as described in Japanese Patent Application Laid-Open No. 7-14841, the applicant of the present invention, a synthetic resin for molding a central portion and a synthetic resin for molding a side portion are extruded by a plurality of extrusions. These extruders are supplied to one die having a special resin distribution channel, and are extruded. Note that the die may be a so-called T-die on a straight line, or an annular die. However, when there is a possibility that the width of the film is changed, it is preferable to form the film by an inflation extrusion molding method using an annular die because the width can be easily adjusted.

Further, when an outer layer is provided on at least one of the film composed of the central portion and the side portion, for example, a single-layer film made of a biodegradable resin is formed as an outer layer separately from the three-divided film. Is bonded to the three-divided film via an adhesive or the like. It can also be obtained by extruding an outer layer at the same time as extruding a three-part film using a co-extruder. When the outer layers are extruded simultaneously using a co-extruder, the number of production steps can be reduced as compared with the case where the outer layers are separately formed and then bonded.

[0021]

According to the multi-film provided by the present invention, when the multi-film is stretched and used, the portion to be covered with soil is made of a resin having a higher decomposition rate than the portion not covered with soil. When the multi-film is collected from the soil, the multi-film is reliably cut at the boundary between both parts. Accordingly, the collected portion has less adhesion of soil and can reduce the burden on the operator, and is also advantageous in recycling the collected multi-film or in disposal by incineration or the like.

[Brief description of the drawings]

FIG. 1 is a plan view (A) of a multi-film according to the present invention.
And (B) is a sectional view taken along aa ′ in (A).

FIG. 2 is a plan view (A) of a multi-film according to the present invention.
FIG. 3B is a cross-sectional view taken along line bb ′ of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-film 2 Tri-divided film 21 Central part 22 Side part 3 Outer layer

Claims (3)

[Claims] 1. A film is divided into three parts parallel to its longitudinal direction into a central part and two side parts sandwiching the central part. The central part has no biodegradability, and the side part has no biodegradability. A multi-film having degradability. 2. The film is divided into three parts parallel to its longitudinal direction into a central part and two side parts sandwiching the central part, and both the central part and the side parts are biodegradable. A multi-film wherein the decomposition rate in the center is lower in the soil than in the side. 3. A biodegradable outer layer is provided on at least one surface of a film divided into three parts at a central portion and two side portions sandwiching the central portion.
Or the multi-film according to 2.