JPH0523945B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a mulching film that covers the ground in summer to promote lowering of soil temperature and prevent weeds from growing when growing crops. More specifically, it is a laminated film consisting of a white or silver reflective film layer that reflects sunlight and a black film layer that completely absorbs the transmission of light from this reflective film layer, with holes and air spaces provided therein. Regarding. Generally, mulching film is used for the purpose of retaining soil moisture, increasing soil temperature, and preventing fertilizer components from being washed away.Although mulching in the summer is effective in retaining soil moisture and preventing fertilizer components from being washed away, There are problems such as the soil temperature becoming too high, making it unsuitable for growing crops, and on the other hand, the growth of weeds. When transparent polyethylene film, which is the most common conventional mulching film, is used in the summer, it is unsuitable for crop cultivation because the penetration of sunlight causes the soil temperature to rise and weeds to grow. Further, although black mulching film has the effect of preventing weeds from growing, it absorbs sunlight and raises the temperature, making it unsuitable for use in summer for the purpose of lowering soil temperature. In order to improve the above-mentioned drawbacks, white mulching films containing titanium oxide and silver polyethylene films containing aluminum powder have been provided as summer mulching films, but these films do not lower the ground temperature sufficiently. Unfortunately, a mulching material that satisfies both of these problems has not been obtained, such as the fact that the weed-preventing effect is insufficient. In addition, films made by vapor-depositing aluminum on polyethylene film or films laminated with aluminum foil are also used for cultivating some crops, but when used, the vapor-deposited film or aluminum foil may peel off or become tattered due to oxidation. It has not been widely used due to its shortcomings, such as being easy to use and also being expensive. In addition, a black and white laminated type mulching film has been provided so far (Utility Model Publication No. 55-38369).
Although it is effective in preventing the growth of weeds, its effect on the drop in soil temperature in summer is still insufficient. The present invention was achieved as a result of various studies aimed at providing a mulching film suitable for summer crop cultivation, which has a function of lowering soil temperature and prevents the growth of weeds. That is, the present invention consists of (1) laminating a thermoplastic resin film containing titanium oxide or aluminum powder and a thermoplastic resin film containing carbon black, and (2) each film has pores (pore diameter 0.3). ~10mmφ,
The present invention relates to a novel mulching film characterized in that the periphery of the mulching film (with a porosity of 0.1 to 5%) is welded, but other parts have an air layer and are not completely adhered. Furthermore, in detail, a thermoplastic resin film containing 10 to 30% by weight of titanium oxide powder or 5 to 30% by weight of aluminum powder and 2 to 10% of carbon black
A laminated film having through-holes with a pore diameter of 0.3 to 10 mmφ and an aperture ratio of 0.1 to 5%, formed by fusing and perforating thermoplastic resin films containing % by weight of The laminated film is a mulching film that is welded around the through holes, has an air layer in other parts, and has an overall thickness of 10 to 75 μm, which prevents soil temperature from dropping in the summer. The present invention also relates to a film that is highly effective in preventing the growth of weeds. FIG. 1 is a perspective view showing an example of the mulching film of the present invention, and FIG. 2 is a sectional view thereof. In the figure, a thermoplastic resin film containing titanium oxide powder or aluminum powder and a thermoplastic resin film containing carbon black are overlapped, and a through hole is formed by fusing and perforating. The area around the through hole is welded to form a heat-sealed part, and the other area is an air layer between the two films. Thermoplastic resins used in the present invention include low density polyethylene, high density polyethylene, ethylene-butene-1 copolymer, ethylene-4-methyl-pentene-1 copolymer, ethylene-vinyl acetate copolymer, Ethylene homopolymers and copolymers such as ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene vinyl acetate-methyl methacrylate copolymer, polypropylene, vinyl chloride resin, etc. can be used. , these can be used alone or in combination. Further, the resins of the titanium oxide or aluminum powder-containing film layer and the carbon black-containing film layer may be the same or different. The bonded film of the present invention can be manufactured by the following steps. A thermoplastic resin composition containing titanium oxide or aluminum powder and carbon black can be obtained by mixing and kneading the powder while melting the resin using an ordinary Banbury mixer, two-roll kneader, or extrusion kneader. It will be done. The obtained resin composition is processed separately into a resin composition containing titanium oxide or aluminum powder and a resin composition containing carbon black by ordinary film processing such as inflation film processing, T-die film processing, and calender processing. Form the film using a machine, or
Using a special two-color inflation film die, each resin composition is extruded from two extruders, and in the two-color die part, a titanium oxide or aluminum powder-containing layer is formed on the half circumference of the film tube, etc. The half circumference of the film is formed into a film by two-color tubular film processing, which becomes a carbon black-containing layer. Among these, the method using a two-color tubular film is preferable because the overlapping step can be omitted. Next, after overlapping a film containing titanium oxide or aluminum powder and a film containing carbon black, a hole with a predetermined diameter and aperture ratio is made using a fusing drilling machine, and at the same time, the surrounding area of the hole is welded. Two types of films are pasted together. The film thickness of each layer is suitably 5 to 30 microns from the viewpoint of cost and handling, and the total film thickness after lamination is preferably 10 to 75 microns. Drilling with a fusing drilling machine has a hole diameter of 0.3 to 10 mmφ in order to both lower the soil temperature and prevent weeds from growing.
The porosity is preferably in the range of 0.1 to 5%, and the pore diameter is in the range of 0.5 to 5%.
A range of 3 mmφ is more preferable. The diameter of the hole to be provided,
If the aperture ratio does not meet the above range, the soil temperature lowering effect is insufficient; on the other hand, if it exceeds the above range,
Although it has an excellent soil temperature lowering effect, it is undesirable because the effect of suppressing the growth of weeds decreases. The mulching film obtained as described above reflects sunlight with the film layer containing titanium oxide or aluminum powder, completely absorbs sunlight with the film layer containing carbon black, and has two layers of film. As a result of the insulation provided by the air layer provided in between and the promotion of air circulation between the inner and outer surfaces of the mulch due to the perforated holes, when mulch is applied to the ground in the summer, the effect of lowering the soil temperature is amplified and the growth of weeds is suppressed. It is possible to prevent this. Therefore, the mulching film of the present invention is most suitable for flatland cultivation of highland lettuce, etc., which are usually grown in cool highlands in the summer, and cultivation of summer/autumn cucumbers, suppressed tomatoes, spinach, etc. Next, the present invention will be explained with reference to Examples, but these Examples are merely illustrative and are not limited thereto. Tests for measuring the soil temperature under the mulching film and observing the state of weed growth shown in the Examples and Comparative Examples were conducted in the following manner. Each film was mulched in a ridge with a width of 1 m, a length of 2 m, and a height of 20 cm, and the soil temperature was measured at a fixed depth of 5 cm from the ground surface. In addition, to observe the state of weed growth, we examined the state of the ridges when the film was removed after mulching for 30 days in the summer. Example 1 Ethylene-butene-1 copolymer (density 0.921,
After kneading 100 parts by weight of titanium oxide (rutile type) powder and 0.3 parts by weight of glycerin monostearate as a dispersant in a Banbury mixer for 10 minutes at a resin temperature of 150 to 160°C, Granulated pellets were produced using an extruder. Hereinafter, the above mixture will be referred to as A mixed resin. In addition, the same ethylene-butene copolymer as above
100 parts by weight of carbon black, 5 parts by weight of carbon black, and 0.1 part by weight of glycerin monostearate as a dispersant were kneaded and granulated in the same manner as above to produce pellets. Hereinafter, this mixture will be referred to as B mixed resin. Next, using a two-color inflation film processing machine equipped with two extruders and two-color dies, the above-mentioned mixed resin A and mixed resin B were put into separate extruders, and the melting zone was set at 220°C. A two-color film having a thickness of 15 microns was molded at a temperature of 200° C., with half of the circumference of the tube-like film being a mixed resin layer A and the other half being a mixed resin layer B. The obtained film consists of A mixed resin layer and B
After the mixed resin layers are folded and overlapped, a 1.5mmφ hole is punched using a fusing drilling machine so that the open area ratio is 0.2%, and the area around the hole is heat-sealed to form a material. A hole-laminated film was obtained. The rolled film is heat-sealed around the hole, and other parts are overlapped, and strictly speaking, there is an air layer. Tests for soil temperature lowering effect and weed growth were conducted by mulching with the B mixed resin layer on the inside (ground side), and the results are shown in Table 1. Example 2 Low density polyethylene (density 0.923, MI=1.5)
100 parts by weight of mica powder (pearl pigment) coated with titanium oxide (pearl pigment) and 0.3 parts by weight of glycerin monostearate as a dispersant were kneaded and granulated in the same manner as in Example 1 to obtain mixed resin pellets A. B was produced in the same manner as in Example 1, except that
A mixed resin was produced, processed into a two-color inflation film, and then a perforated bonded film was obtained using a fusing punch. Table 1 shows the performance of the obtained film. Example 3 Example 1 except that the titanium oxide used in the mixed resin A in Example 1 was changed to 15 parts by weight of aluminum powder.
A perforated bonded film was obtained using the same method. Table 1 shows the performance of the obtained film. Comparative Example 1 Only the mixed resin A of Example 1 was processed into a film using a normal inflation film processing machine to a thickness of 30 mm.
A micron monolayer film was obtained. Table 1 shows the performance of the obtained film. Comparative Example 2 Only the mixed resin A of Example 3 was processed into a film using a normal inflation film processing machine to a thickness of 30 mm.
A micron monolayer film was obtained. Table 1 shows the performance of the obtained film. Comparative Example 3 An A/B laminated film was obtained using the A/B mixed resin used in Example 1 using a two-layer inflation film processing machine equipped with two extruders and a two-layer die. Ta. The obtained film had a mixed resin layer A (15 microns thick) and a mixed resin layer B (15 microns thick) completely fused and laminated. The performance of this film was tested using the same method as in Example 1 and is shown in Table 1. Comparative Example 4 An A/B laminated film was obtained using a two-layer inflation film processing machine equipped with two extruders for mixed resin A and mixed resin B used in Example 3 and a two-layer die. The obtained film has a mixed resin layer A (15 microns thick) and a mixed resin layer B (15 microns thick).
were completely fused and laminated. The performance of this film was tested using the same method as in Example 1 and is shown in Table 1. Comparative Example 5 Ethylene-butene-1 copolymer (density 0.921 MI
= 2 g/10 minutes) using an ordinary inflation processing machine to obtain a transparent film with a thickness of 30 microns. Table 1 shows the performance of the obtained film.

[Table] As is clear from Table 1, it is clear that the present invention has a superior soil temperature lowering effect compared to conventional mulching films, and is also effective in preventing the growth of weeds.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the mulching film of the present invention, and FIG. 2 is a sectional view thereof. ...resin film layer containing titanium oxide powder or aluminum powder, ...resin film layer containing carbon black, ...perforation by fusing perforation,
...Heat seal section, ...air layer.

Claims (1)

[Claims] 1. By fusing and perforating a thermoplastic resin film containing 10 to 30% by weight of titanium oxide powder or 5 to 30% by weight of aluminum powder and a thermoplastic resin film containing 2 to 10% by weight of carbon black in a superimposed state. Formed pore diameter 0.3~10mm
φ, a laminated film having through holes with a porosity of 0.1 to 5%, the laminated film is welded around the through holes, other parts have an air layer, and the entire laminated film is welded. Characterized by a wall thickness of 10 to 75μ,
Ground temperature lowering mulching film.