JPH08214713A - Multifunctional mulch film - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a multifunctional multi-film that is multifunctional and low-cost, which prevents weeds from overgrowth and has the same soil temperature raising function as transparent multi-film. [Structure] Absorbance at 500 nm (A ₅₀₀ ) and 800
The iron oxide particles having an absorbance (A ₈₀₀ ) ratio A ₅₀₀ / A ₈₀₀ at 4.0 nm of 4.0 or more, and an organic content of any one selected from purple, blue, and green are 1.
A multifunctional multi-film having a soil temperature increasing portion 21 made of a thermoplastic resin contained in an amount of 0 to 5.0 wt% in a strip shape in the longitudinal direction of the film 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a multi-film laid on ridges or the like for improving the cultivation efficiency of agricultural products, more specifically, a multi-functional film having different performances at predetermined positions of the film in a strip shape in the longitudinal direction. Regarding mulch film.

[0002]

2. Description of the Related Art Conventionally, multi-films having various functions have been proposed in order to efficiently grow agricultural products. For example, a transparent mulch film that has the effect of raising soil temperature, a black film that prevents weeds from growing,
Examples include silver mulch film that has a pest repellent effect, and white mulch film that is used to control soil temperature in the summer.

However, since a multi-film having a single structure has a limit in satisfying various required functions, a so-called color-arranged multi-film having different functions even in a single film has attracted attention. It's starting. For example, when the film is viewed from above, an agricultural mulching film colored in milky white on both sides and black or silver in the center with respect to the longitudinal direction (Actual Kaihei 6-38).
No. 484), or a multi-film for agriculture (Japanese Utility Model Laid-Open No. 6-38485) having black or silver on both sides and milky white at the center, in which the color arrangement is reversed.

From the time of sowing or planting to the growing season, these films are located in the soil where the hair roots of the crop cover the central part of the mulch film, and both sides of the mulch film are grown when the crop has grown considerably. It was proposed focusing on the fact that it exists in the soil covered with, the former is a crop that requires soil temperature rise in the early stage of growth when the central part is black and then soil temperature suppression (for example, It is suitable for crops that are planted in spring and harvested in summer. When the latter is also black on both sides, contrary to the mulch film described above, it is necessary to suppress the soil temperature in the early stage of growth and then increase the soil temperature. Suitable for crops (eg crops planted in summer and harvested from autumn to winter).

However, since these mulch films are provided with a weed-preventing function by forming colored films that are difficult to transmit sunlight, they have not been able to obtain the same effect of raising the soil temperature as transparent films.

Further, the present inventors have previously proposed Japanese Patent Application No. 6-2134.
No. 50 proposed an agricultural mulch film made of a thermoplastic resin containing specific iron oxide particles and an organic pigment. However, since this film has a single structure, it is difficult to impart a new function depending on the type of crop and the time of use of the mulch film, and there is a problem that the cost becomes high.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a multifunctional multi-film that prevents weeds from overgrowth and has the same function of increasing the soil temperature as transparent mulch film, and that is multifunctional and low-cost. Subject.

[0008]

As means for solving the above-mentioned problems, in the present invention, the ratio A ₅₀₀ / A ₈₀₀ of the absorbance at ₅₀₀ nm (A ₅₀₀ ) and the absorbance at 800 nm (A ₈₀₀ ) is 4.0 or more. The weed-preventing / ground temperature rising part consisting of a thermoplastic resin containing 1.0 to 5.0 wt% of each iron oxide particle and one of the organic pigments selected from purple, blue, or green is the longitudinal direction of the film. Provided is a multi-functional multi-film, which is formed in a strip shape in the direction, and the multi-functional multi-film is a multi-layer film having a transparent layer in at least one outermost layer. The multi-functional multi-film is provided, and further, the multi-functional multi-film, wherein the pest repellent is mixed in the transparent layer. The multifunctional multi-film provided, further comprising the weed-preventing / ground temperature increasing portion provided substantially at the center in the width direction of the film.

That is, the present inventors have found that a film made of a thermoplastic resin containing iron oxide having a specific absorbance and a colored pigment having a specific hue is necessary for photosynthesis of weeds.
We found that it blocks rays in the region of ~ 700 nm well, but does not contribute to the overgrowth of weeds and effectively transmits rays in the region of 700 nm or more, which is effective in raising the soil temperature, and more efficiently performs such functions. As a result of earnest research on the structure of a multi-film capable of exerting its effect, the present invention has been achieved.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view (A) and a plan view (B) showing an example of a multifunctional multi-film according to the present invention. The multifunctional multi-film of the present invention has the color arrangement layer 2 in the film structure. The color arrangement layer 2 includes a weed prevention / ground temperature rising portion (hereinafter referred to as a ground temperature rising portion) 21 and another portion (hereinafter referred to as another portion) 22. The position of the ground temperature raising portion 21 in the color arrangement layer 2 may be appropriately determined according to the place and time when the mulch film is stretched, but when the multifunctional mulch film is continuously manufactured by the coextrusion method described later, Due to the above reasons, the ground temperature raising portion 21 becomes a strip shape in the longitudinal direction of the film. Particularly, as shown in FIG. 1, it is preferable to provide the soil temperature raising portion 21 at the center of the mulch film because the land near the seed can be efficiently warmed and weeds near the seed can be prevented. The width of the soil temperature rising portion 21 at this time is preferably about 10 to 50 cm, though it depends on the tension of the roots of the crop, and if the width is narrower than this, a sufficient effect cannot be obtained, and the width is wider than this. However, not only will there be little improvement in the effect, but it will also lead to higher costs.

For the other portion 22 of the color arrangement layer 2 other than the ground temperature raising portion 21, a resin conventionally used for a mulch film can be appropriately selected and used. For example, when the other portion 22 is formed of a black thermoplastic resin containing carbon black or the like, weeds can be prevented from growing over a wide area in the mulch film, and when the other portion 22 is formed of a transparent resin, the other portion 22 It can be expected to have the function of raising the soil temperature in the entire area covered by the film. Furthermore, if the other portion 22 is formed of a thermoplastic resin containing a silver pigment, the pest repellent effect is enhanced.

The granular magnetite particles are 500 nm.
The iron oxide has an A ₅₀₀ / A ₈₀₀ ratio of absorbance (A ₅₀₀ ) at 800 nm and absorbance at 800 nm (A ₈₀₀ ) of less than 4.0, but due to its unique photo-semiconductor property, it absorbs ultraviolet rays and promotes the growth of crops. Emit far-infrared rays that promote. By utilizing this property, the granular magnetite particles and carbon black that prevents the deterioration of the resin due to the granular magnetite particles are added to the thermoplastic resin to form the other portion 22, and the multifunctional multi-film 1 is grown by far infrared rays. It will also have a promoting effect. The amount of granular magnetite particles or carbon black added at this time was 1-10 wt% for granular magnetite particles and 0.5 for carbon black.
It is preferably about 4.0 wt%.

Further, the multifunctional multi-film 1 of the present invention may be a single-layer film consisting of only the color arrangement layer 2, but there is no problem. However, when the transparent layer 3 is provided on at least one of the color arrangement layers 2, the color arrangement layer 2 is formed. This is preferable because the strength of the seam 23 is improved. Furthermore, it is particularly preferable to mix a pest repellent into the transparent layer 3 because it can prevent the pests from flying. As repellents mixed at this time, pyrethrins, pyrethroids such as allethrin, and hoxime, pyridafenthion, organophosphorus insecticides such as tetrachlorvinphos, and ovacunon, nomiline, deoxylimonin extracted from natural bark and the like, Further, a mixed agent of 3,6-dichloropyritazine and parachlorometaxylenol can be exemplified.

The thermoplastic resin used in the multifunctional multi-film of the present invention can be applied without any particular limitation as long as it is a thermoplastic resin suitable for ordinary extrusion molding methods and calender molding, and examples thereof include low density polyethylene and linear polymers. Examples thereof include polyethylene resin such as low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer pair, polypropylene resin or polyvinyl chloride resin. Among these, it is preferable to use a polyethylene resin that can be incinerated after use and can be obtained at low cost, and linear low-density polyethylene is particularly preferable.

As the iron oxide particles contained in the soil temperature raising portion 21 of the present invention, the absorbance at 500 nm (A ₅₀₀ ) and the absorbance at 800 nm of the film obtained by adding and mixing the iron oxide particles to the above-mentioned thermoplastic resin. (A ₈₀₀ )
There is no particular limitation as long as the ratio A ₅₀₀ / A _800, which is a ratio of 4.0, is 4.0 or more, and iron oxide particles satisfying such conditions include, for example, hematite having an average particle diameter of 80 to 150 nm (α- Fe ₂ O ₃ ) particles may be mentioned. When the average particle size is less than 80 nm or exceeds 150 nm, A ₈₀₀ is constant or decreases, but A ₅₀₀ is greatly decreased, so that the value of A ₅₀₀ / A ₈₀₀ is less than 4.0. A ₅₀₀
When the value of / A ₈₀₀ is less than 4.0, it means that the effect of preventing overgrowth of weeds or the effect of increasing soil temperature is reduced, which is not preferable.

The shape of the particles may be spindle-shaped, needle-shaped, plate-shaped, spherical, hexahedral, octahedral, polyhedral, indeterminate, or any other so-called granular shape, but for photosynthesis of weeds. Granular particles that are difficult to transmit the necessary light rays in the region of 400 to 700 nm are preferable.

As the organic pigment contained in the ground temperature raising part 21 together with the iron oxide particles, any organic pigment selected from purple, blue or green can be used. Examples of such organic pigments include dioxazine violet, phthalocyanine blue, diamond green lake, pigment green B, green gold, and phthalocyanine green. In particular, phthalocyanine blue is preferable because it has a low light transmittance in the wavelength range of 500 to 700 nm and a considerably high transmittance in the wavelength range of 900 nm or more.

The amount of the iron oxide particles and the organic pigment added to the thermoplastic resin in the ground temperature raising section 21 is determined by the thickness of the multifunctional multi-film 1, the type of the iron oxide particles or the organic pigment to be used, or the oxidation used in combination with each other. Depending on the amount of iron particles or organic pigment added, each is 1.0 to 5.
0 wt%, and particularly preferably 1.5 to 3.5 wt%. If iron oxide particles or organic pigments are added in excess of 5.0 wt% each, not only the transmittance of solar rays is lowered as a whole, but the effect of raising the soil temperature is lowered and the cost is also increased, which is not preferable. . On the other hand, if it is less than 1.0% by weight, the transmittance particularly near the wavelength of 550 to 700 nm becomes high and the effect of preventing overgrowth of weeds decreases, which is not preferable. In addition, the total amount of iron oxide particles and organic pigments added is preferably 2.5 to 8.0 wt% in view of the effect of the additives and the film strength.

Further, in the present invention, in addition to iron oxide particles, organic pigments, pest repellents, conventionally known surface active agents, coupling materials, lubricants, antiblocking agents, weathering agents, ultraviolet absorbers, stabilizers. It is of course possible to add the like.

In the method for producing the multifunctional multi-film 1 of the present invention, for example, the film to be the ground temperature raising part 21 and the film to be the other part 22 are separately formed in advance, and these are formed into a desired shape. Obtained by pasting. Further, as an industrial manufacturing method capable of continuous mass production, an extrusion molding method using a plurality of extruders can be exemplified. For example, in the case of molding a single layer film composed of only the color arrangement layer 2, The resin for the soil temperature raising part 21 and the resin for the other part 22 are supplied to one extruder, and these resins are formed into a striped film by the inflation extrusion molding method or the T-die extrusion molding method, and cut into a desired width. Good to do. Further, for the purpose of improving weather resistance and repelling harmful insects, the multifunctional multi-film 1 of the present invention is preferably a multilayer film having a transparent layer 3 in at least one layer, and the transparent layers are arranged so as to sandwich the color arrangement layer 2 therebetween. A multilayer film having 3 in both outer layers is more preferable. In this case, at least three extruders may be used to supply the resin for the transparent layer 3 in addition to the above resins to perform coextrusion molding. The thickness of the multifunctional multi-film 1 differs depending on the intended use and has a close relationship with the light transmittance, so it is necessary to carefully select it.
It is generally about μm.

[0021]

In general, in order for the mulch film to obtain a sufficient weed-preventing function, 400-700 necessary for photosynthesis of weeds is required.
It is said that it is necessary to block light rays in the region of nm, and to transmit light rays in the region exceeding 700 nm in order to efficiently raise the ground temperature. Specifically, (1) the transmittance in the region of 400 to 700 nm does not exceed 25%, and (2) 900
That is, the average transmittance in the region of ˜1,500 nm is 60% or more.

By the way, the iron oxide particles used in the multifunctional multi-film of the present invention absorb light rays in the ultraviolet region similarly to titanium oxide, zinc oxide, etc., and therefore have a low short-wavelength light transmittance, and thus visible light rays and near infrared rays. It has the property of increasing the light transmittance as the wavelength becomes longer in the region. However, since iron oxide particles have various crystal structures and color tones as compared with titanium oxide, zinc oxide, etc., mainly by selecting the type, crystal shape, and particle size of the iron oxide particles, the particle size of 550 nm or less is mainly selected. It is possible to block light by controlling the light transmittance of the region to some extent. In FIG. 2, 2.0 wt% of iron oxide particles (manufactured by Toda Kogyo Co., Ltd.) shown in Table 1 was added to and mixed with linear low-density polyethylene to produce a thickness 2
Spectral transmittance curve of 0μm film (Hitachi, U
Measured with a 3500 spectrophotometer. ). Also, A ₅₀₀ / A ₈₀₀ of iron oxide particles is 500 nm and 800 nm
The absorbance (A) obtained by the following equation was used to calculate the transmittance (% T) in the above equation. A = log (100 /% T)

[0023]

[Table 1]

In addition, phthalocyanine blue (produced by Sumika Color Co., Ltd., trade name: Blue SPEM-503) 5.5
FIG. 3 shows a spectral transmittance curve of a film having a thickness of 20 μm prepared by adding wt% to linear low-density polyethylene and mixing them.
Shown in Generally, 5 films are purple, blue and green.
The transmittance of visible light of 50 to 800 nm is low, 800 n
The transmittance sharply increases in the region of m or more.

Therefore, the ratio A ₅₀₀ / A ₈₀₀ of the absorbance at 500 nm and 800 nm is 4.0 or more, that is,
550 to 80 iron oxide particles having spectral transmittance characteristics in which the transmittance sharply increases from 500 nm to 800 nm
If a combination of organic pigments selected from purple, blue, and green, which have a low transmittance of 0 nm visible light and a sharp increase in the transmittance of 800 nm or more, are used in the 400-700 nm region due to their synergistic effect. The maximum value of the transmittance is 25%, and the multi-film can be provided with a characteristic that the average transmittance in the near infrared region of 900 to 1,500 nm exceeds 60%. FIG. 4 shows a spectral transmittance curve of a film (all having a thickness of 20 μm) obtained by using the resin raw material having the composition shown in Table 2. However, L in the table
DPE means a linear low density polyethylene resin.

[0026]

[Table 2]

Each of the films thus obtained had an average transmittance of less than 25% at 400 to 700 nm,
Since the average transmittance from 00 to 1500 nm is 60% or more, it is effective in preventing overgrowth of weeds and increasing soil temperature.

[0028]

EXAMPLES The present invention will be described below with reference to examples. The performance of the mulch film of the present invention was evaluated by the following method.

<Weed-preventing effect> Various mulch films were laid on agricultural land in Marugame City, Kagawa Prefecture on April 16, 1994, and 3
It was evaluated by the condition of weed overgrowth after 0 days. ○ ・ ・ ・ No weeds are growing △ ・ ・ ・ Weeds are growing in small quantity × ・ ・ ・ Weeds are growing in large quantity <Ground temperature measurement> From May 8, 1994 to May 16, 1994 During this period, various mulch films were laid and evaluated by the average value of the temperature in the coated soil of 5 cm at 5 am, 2 pm and 6 pm of the day.

In the examples and comparative examples, Table 2 is partially shown.
The resin shown in was used. A carbon black masterbatch (manufactured by Tokyo Ink Co., Ltd., product name: PEX3500C) was used as a black pigment, and an aluminum foil piece kneaded masterbatch (manufactured by Sumika Color Co., Ltd., product name: 8K240AL) was used as a silver pigment.

Examples 1-5, Comparative Examples 1-5 Linear low-density polyethylene (manufactured by Sumitomo Chemical Co., Ltd.,
Product name: Sumikasen LFR144E, MI = 0.8g /
10 minutes, a density of 0.920 g / cm ³ ) was compounded as shown in Table 3 and supplied to an extruder to produce mulch films A to J by an inflation molding method. The resin symbols a, c, and e in the table correspond to the resin symbols in Table 2, and LDPE means linear low-density polyethylene. Manufacturing conditions are processing temperature 200 ℃, extrusion rate 20kg / h
r, a blow ratio of 3.0, and a take-up speed of 12 m / min.

Note that each of A to D and F to J has a thickness of 2
It is a single-layer film with a width of 0 μm and a width of 1,500 mm.
This film is a multi-layer mulch film having a transparent layer made of linear low-density polyethylene in both outer layers. The multilayer mulch film also has a thickness of 20 μm and a width of 1,500 mm. A to F are so-called color arrangement multi-films which can be divided into both sides and the center in the longitudinal direction of the film.

[0033]

[Table 3]

Further, Table 4 shows the results of evaluation of the effect of preventing the overgrowth of weeds and the effect of increasing soil temperature of the mulch films of A to J by actually laying them on agricultural land.

[0035]

[Table 4]

As is clear from Tables 3 and 4, the multifunctional multi-films A to E of Examples 1 to 5 exhibit a sufficient soil temperature raising function and weed prevention function in the vicinity of the central portion of the film. There is. Further, as in Examples 1 to 3, L is provided on both sides.
It can be seen that the provision of the transparent resin portion composed only of the DPE resin has the effect of raising the ground temperature over the entire surface of the film. Further, when black portions containing carbon black are provided on both sides as in Example 5, weeds are prevented from growing over the entire surface covered with the multifunctional mulch film. In addition, when both sides are made silver as in Example 4, a pest repellent effect is also seen.

[0037]

[Effect] The multi-functional multi-film according to the present invention is 40
Light transmission in the region of 0 to 700 nm is small, 700 n
Since it has a soil temperature rising part with good light transmission in the area exceeding m, it has both a weed prevention function and a soil temperature rising function.

Further, the entire film is not made of a single resin, but is a strip in the longitudinal direction of the film, part of which is the ground temperature rising part, and the remaining part is a part having another function, which is more complicated. Various functions can be added to the film. Further, it is possible to prevent the ground temperature rising portion containing the expensive additive from having an unnecessarily large area, and to suppress an increase in manufacturing cost.

Furthermore, by providing a transparent layer on at least one outermost layer of the film, it is possible to prevent insects from flying.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (A) and a plan view (B) showing an embodiment of a multifunctional multi-film according to the present invention.

FIG. 2 is a spectral transmittance curve of a film obtained from a resin obtained by adding iron oxides α to δ shown in Table 1 to a linear low-density polyethylene.

FIG. 3 is a spectral transmittance curve of a film obtained from a resin obtained by adding phthalocyanine blue to linear low density polyethylene.

FIG. 4 is a spectral transmittance curve of a film obtained by using a resin raw material having a composition shown in Table 2.

[Brief description of symbols] 1 Multifunctional multi-film 2 Color layer 21 Weed prevention / ground temperature rise part 22 Other part 23 Seam 3 Transparent layer

Claims (4)

[Claims] 1. Absorbance at 500 nm (A ₅₀₀ ) and 8
Absorbance at 00 nm (A ₈₀₀ ) ratio A ₅₀₀ / A ₈₀₀
Oxide and iron oxide particles having a value of 4.0 or more, and any organic pigment selected from purple, blue, or green, which are 1.0 to 5.0 wt% each, are added to the weeds to prevent weeds and increase the soil temperature. The multifunctional multi-film, wherein the part is formed in a strip shape in the longitudinal direction of the film. 2. The multifunctional multifilm according to claim 1, wherein the multifunctional multifilm is a multilayer film having a transparent layer as at least one outermost layer. 3. The multifunctional multi-film according to claim 2, wherein a pest repellent is mixed in the transparent layer. 4. The multi-functional multi-film according to claim 1, wherein the weed prevention / ground temperature rising portion is provided substantially in the center in the width direction of the film.