JPS60152540A - Ultraviolet-screening agricultural film - Google Patents

Abstract

PURPOSE:To provide the titled film which causes no whitening and can keep an excellent ultraviolet-screening capability over a long period , by incorporating a particular ultraviolet light absorber in a linear low density PE. CONSTITUTION:100pts.wt. linear low-density PE with a density of 0.890-0.940g/ cm<3> and an MI of 0.1-20, 0.3-2.0pts.wt. ultraviolet light absorber comprising benzotriazole derivatives of formula I or II (wherein R1 is 3-5C branched alkyl; R2, R3 are 1-8c straight=chain or branched alkyl), and, if necessary, a slipping agent, antioxidant, antistatic agent, etc. are incorporated to mold in a film, yielding an ultraviolet-screening agricultural film with a thickness of 15-75mu which has an absorption peak in the region of wavelengths up to at least 290- 400nm and a degree of screening light of 60% or more at the absorption peak, and can permeate visible rays with a wavelength of 500nm or above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultraviolet-shielding agricultural film made of linear low-density polyethylene, and more specifically,
A specific benzotriazole-based UV absorber with excellent properties such as weather resistance, UV IS shielding ability, no whitening phenomenon, long-term tear strength retention, impact resistance, stiffness, dust resistance, etc. The present invention relates to an ultraviolet-shielding agricultural film made of near low density polyethylene containing a specific amount of an agent.

In order for plants to grow in a healthy manner, they must be provided with light air and water, as well as an appropriate temperature and appropriate amount of nutrients.

In recent years, with the development of science and technology, in the field of plant culture technology, there are improvements in the light quality control of the plant cultivation environment, such as increasing carbon assimilation by supplying COI, promoting root development by supplying oxygen in the soil, and automatically supplying water. Research and its development are progressing at a remarkable pace.

In research on light quality control in plant cultivation environments, certain types of plant pathogenic bacteria, such as imote bacterium, which kills rice, and sesame leaf blight bacterium; eggplant, tomato, kirari, strawberry, watermelon, melon, green pepper, lettuce, Chinese cabbage, carrot, and burdock , Sclerotinia bacterium that occurs on fruit vegetables such as radish, leafy vegetables, root vegetables, etc.; B) IJ theis bacterium, anthracnose bacterium, vine blight,
There is a close relationship between the growth of molds such as black mold fungi and leaf spot fungi and the wavelength of ultraviolet rays, and such molds will not grow under conditions where UV rays with wavelengths of 370 to 380 nm and below are completely shielded. This has already been reported.

The present applicant has previously proposed the following formula as an agricultural film capable of substantially completely blocking the transmission of ultraviolet rays with wavelengths of 380 nm and below, which is useful for controlling the growth of plant disease-causing fungi as described above. In the formula, the lump represents a branched alkyl group having 3 to 5 carbon atoms, and R1 represents a linear or branched alkyl group having 1 to 8 carbon atoms. IJ azole-based external radiation absorber 2.
We proposed an agricultural film made of vinyl chloride resin film containing less than 5 parts of it (Special Publication No. 53-47).
Publication No. 383).

Additionally, the present applicant has proposed that an agricultural film that substantially blocks the transmission of ultraviolet rays of wavelengths of at least 370 nm and below may be used to prevent dehiscence of tomatoes grown in facilities under the covering of such agricultural film (Japanese Patent Publication No. 55 -12208 Publication)
, vertical cultivation of chives, chives, etc. (Tokuko Sho 55-1020
(Japanese Patent Publication No. 3), To accelerate the head formation and increase the head weight of lettuce or Chinese cabbage (Japanese Patent Publication No. 56-46375), and to increase the sugar content of fruit (Q', Publication No. 53-75039).
, discovered that it has a remarkable cultivation effect in preventing the aging of green peppers (Japanese Unexamined Patent Publication No. 53-127126).

A mulching cultivation technique using suyui film, which is spread closely to the soil surface and then removed from the soil surface, is also known.

Examples of films used in such mulching cultivation include transparent films made of polyethylene, and films colored black or green. Mulching with the film provides advantages such as keeping the soil warm, retaining moisture in the soil, preventing fertilizer nutrients from being washed away, preventing soil from bouncing back, and suppressing the growth of weeds.

Recently, UV-shielding mulching materials have also been proposed. For example, in Japanese Patent Application Laid-Open No. 53-98242, 370 nm
JP-A-53-124556, a method for cultivating root vegetables characterized by cultivating root vegetables under mulch while being covered with a mulching covering material made of a transparent film capable of substantially blocking light of wavelengths of At least 3
Transparent mulching covering materials made of synthetic resin films or plates that substantially block the transmission of ultraviolet rays with wavelengths of 70 nm or less have been proposed.

However, polyethylene film for industrial use that contains a large amount of ultraviolet absorber can be used without any problems with normal cleaning, but the surface of the film or the entire film becomes cloudy during the severe cold of winter or the high temperature of summer. It was found that a so-called bleaching phenomenon occurs.

This whitening phenomenon occurs particularly strongly in thin films, which has various drawbacks such as reduced light transmittance, poor dust resistance, and reduced ultraviolet shielding ability, and the reality is that this film has not been put into practical use. 3. The present inventors have reported on the improvement of UV-shielding polyethylene film without whitening phenomenon,
As a result, it was discovered that when specific amounts of a specific polyethylene and a specific ultraviolet absorber are used in combination, the two interact to prevent the whitening phenomenon.

According to the present invention, the following formula 1 is contained: 0.3 to 2.0 parts by weight per 100 pieces of linear low density polyethylene, and at least 2
A UV-shielding agricultural film is provided, which has an absorption maximum in the wavelength range of 90 to 400 nm and has a light shielding rate of 60% or more at the absorption maximum.

The ultraviolet-shielding agricultural film provided by the present invention has extremely excellent weather resistance 1, can maintain excellent ultraviolet-ray shielding ability for a long period of time despite changes in outdoor weather, and has no bleaching properties. No phenomenon, impact resistance,
It is a strong film that is dust-proof and maintains tear strength over a long period of time.The use of the film of the present invention in agricultural tunnel cultivation, lining cultivation in vinyl greenhouses, and mulching cultivation can prevent pesticide pollution, promote growth, etc. The contribution to the agricultural field is extremely large.

Linear low density polyethylene (hereinafter sometimes abbreviated as L-LDPE) used in the present invention is a type of low density polyethylene, and it contains ethylene, 1-butyne, 1
- It is a copolymer of C8 to CIO α-olefins such as hexene, 1-octene, and 4-methyl-1-pentene, either alone or in combination. L-LDPE is a polymer based on α-olefins whose main chains are connected almost linearly and are copolymerized in places.

Compared to conventional low @ L polyethylene, L-LDPE has higher tear strength, impact strength, and
Excellent back strength etc.

In the present invention, any L-LDPE can be used with an i density of 0.
．． 890~0.940 tA, 0.1~20 y/1
0 also has good q, and the density is 0.91 to 0.9351,
More preferably, it is 0.3 to 1ξf/%. In addition, the amount of α-olefin that undergoes large polymerization with ethylene is 3 to 2 per 100 parts of the total amount of ethylene and d-olefin.
It is preferably 5 parts by weight, and more preferably 5 to 15 parts by weight. The density and melt index of L-LDPE are measured according to JISK-6760 (polyethylene test method) (density: JISK-7112 melt index; applied mutatis mutandis to JIS K-7210).
If the amount of α-olefin in the copolymer in E is in excess of 25 parts, when formed into a film, the strength of the film, such as yield stress and breaking stress, will be poor. On the other hand, if the amount is less than 3M parts, the desired strength will not be obtained and a bleeding phenomenon of the ultraviolet absorbent will occur.

Further, in the present invention, L-LDPE and other resins may be blended as long as the whitening phenomenon does not occur.

The thickness of the agricultural film of the present invention is preferably 15
-75μ Particularly preferably 20-50μ, more preferably 25-40μ; if it is less than 15μ, the film strength will be insufficient and the present invention will not work. The "absorption maximum" of "ultraviolet ray shielding film for industrial use, which is characterized by having a maximum and a light shielding rate of 60 or more at the absorption maximum" It refers to the part that exhibits the maximum absorbance or extinction coefficient within a wavelength range. In addition,
If the top of the peak 11 indicating the absorption maximum is flat, the center point of the flat portion will be referred to as the absorption maximum.

The absorption maximum is at least 290 to 400 nm, preferably 300 to 400 nm, particularly preferably 3
In a preferred embodiment, the wavelength range is from 30 to 400 nm.

Furthermore, the light shielding rate at the absorption maximum includes not only the case where 100 lines are completely shielded, but also the case where at least 60% or more, preferably 70% or more, particularly preferably 80 lines or more, and still more preferably 90% or more is shielded. It is used in the sense of

Thus, according to the invention, suitable films have a wavelength of at least 360 nm and below, particularly preferably 370 nm.
m and below, more preferably 380 nm and below, and substantially blocks light at wavelengths of 500 nm and below;
and wavelengths above preferably 450 nm %
Particularly preferably 420 nm, more preferably 400 nm
It is a film that can substantially transmit light having a wavelength of m or more.

The phrase "substantially blocks ultraviolet light in the wavelength range of at least 360 nm and below" refers to 300 to 3 fi Onm.
Not only does it completely block 100% of the light in the wavelength range, but it also means that it allows the transmittance of light in the wavelength range to be blocked by up to 60 lines, preferably 70 lines, and more preferably 90% or more. use.

In addition, "can substantially transmit light having a wavelength of 500 nm or more" means not only transmitting 1()0% of the light of the wavelength, but also transmitting the light of the wavelength by at least 60%, especially 70%, and even 80%. The meaning also includes being transparent.

The ultraviolet absorber of formula (1) used in the present invention represents a branched alkyl group having 3 to 5 carbon atoms, such as isopropyl, inbutyl, tertiarybutyl, inamyl, and tertiaryamyl group.

Java sparrow represents a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl isopropyl, isobutyl, tert-butyl, n-butyl, isoamyl, tert-aryamyl, n-amyl. , normal hexyl, isohexyl, normal heptyl, isoheptyl, normal octyl, isooctyl, tertiary octyl, and the like.

Further, as the ultraviolet absorber of the formula [■] used in the present invention, R3 represents a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, normal propyl, isofuropyl, isobutyl, tertiary alkyl group, etc. These include butyl, normal butyl, isoamyl, tertiary amyl, normal amyl, normal hexyl, isohexyl, normal heptyl, isoheptyl, normal octyl, isooctyl, tertiary octyl, and the like. These I or H
Examples of benzotriazole derivatives are as follows.

2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-
(2'-hydroxy-5'-amylphenyl)hencytriazole, 2-(2-hydroxy-3-5'-ditertiary-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3', 5'-cyisozutylphenyl)-5-chlorobenzotriazole,
2-(2-hydroxy-3゜5-diisoamylphenyl)-5-10lopenzotriazole, 2-(2'-hydroxy-3',5'-ditertiary-amylphenyl)
-5-Chlorobenzotriazole, 2-(2-hydroxy-3-isofuropyru-5-methulfenyl)-5-1
0 lobensotriazole, 2-(2-hydroxy-3-
Isopropyl-s'-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-31-isofuropylphenyl-5-octylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3'-inbutyl- 5'-methylphenyl)-5-chlorobenztriazole, 2-(2-hydroxy-3-ynbutyl-5
-propylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-ynbutyl-5-ynamylphenyl)-5-chlorobenzotriazole, 2-
(2'-hydroxy-3-tert-butyl-5'-
methylphenyl)-5-chlorobenzotriazole, 2
-(2'-hydroxy-3-tert-butyl-5'
-isopropylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3'-tert-butyl-5'-amylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-tert-butyl) -5-ynoctylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-ynamyl-
5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-isoamyl-5-butylphenyl)-5-chlorobenzotriazole, 2-(2
-hydroxy-3-isoamyl-5-tert-amylphenyl)-5-chlorobenzotriazole, 2-(
2-Hydroxy-3-tert-amyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2
-Hydroxy-3-tertiaryamyl-5-inbutylphenyl)-5-chlorobenzotriazole, 2- (
2'-hydroxy-3-tert-amyl-5-isoamylphenyl)-5-chlorobenzotriazole, etc., preferably 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy -3-51-Ditasha IJ-7'tylphenyl)-
5-chlorobenzotriazole, 2-(2-hydroxy-3-tert-phthyl-5-methylphenyl)-5
-chlorobenzotriazole, etc.

Further, in the present invention, it is preferable to use two or more of the benzotriazole derivatives of formula (I) and 00 in combination.

If two or more of these UV absorbers are used together,
Suitable compounds include 2-(2-hydroxy-3.5-ditertiary-7'tylphenyl)-5-chlorobenztriazole and 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5- Chlorobenzotriazole and the like.

Furthermore, in the present invention, it is particularly preferable to use three or more of the benzotriazole visiting conductors of formula (I) and 0 in combination.
Particularly suitable for use in combination of three or more u2-(2-hydroxy-5-methylphenyl)benztriazole, 2
-(2-hydroxy-3゜5'-ditertiary-7'tylphenyl)-5-chlorobenzotriazole, 2-(
2'-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole, and the like.

It is also possible to use in combination at least one of the UV absorbers of formulas (1) and 11 of the present invention with benzotriazole-based UV absorbers or benzophenone-based UV absorbers other than those of formulas (1) and 11. .

For example, benzotriazole-based ultraviolet absorbers other than formulas 1 and 11 above include 2-(2-hydroxy-3,5-
dimethylphenyl)-penztriazole, 2-(2-
Hydroxy-3,5-dimethylphenyl)-5-meth)oxybenztriazole, 2-(2-hydroxy-5-cyclohexylphenyl)-benzotriazole, 2-(
2-hydroxy-3', 5'-dichlorophenyl)benzotriazole, 2-(2'-hydroxy-415
'-dichlorophenyl)penztriazole, 2-(2
-Hydroxy-5-phenylphenyl)penztriazole, 2-(2-hydroxy-5-methoxyphenyl)
-5-merhensotriazole, 2-(2-hydroxy-3,5-diisopropylphenyl)-5-chlorobenztriazole, 2-(2-hydroxy-3'-
isohexyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-neoheptyl-5'-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3 -isooctyl-5-ethylphenyl)-5-chloropenttriazole and the like.

Examples of benzophenone ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4n.
-Octoxybenzophenone, 2-hydroxy-4-methoxy-2-carboxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4
, 4-dimethoxybenzophenone, 2-hydroxy-4
-benzoyloxybenzophenone, 2,2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4
-methoxy-5-sulfonebenzophenone, 2,2,4
゜4-f) Dihydroxybenzophenone, 2.2-
Examples include hydroxy-4,4'-dimethoxy-5-sodium sulfobenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-5-chlorobenzophenone, etc.O Also, hydroquinone-based ultraviolet absorbers, salicylic acid-based ultraviolet rays Absorbers and other UV absorbers may be used together.

The formulation Id of the ultraviolet absorber that can be used in the present invention varies depending on the type and thickness of the L-LDPE resin used, and must be appropriately determined depending on each case. , generally considering the desired thickness of the coating material of the present invention, the total tN of L-LDPE resin:
As the total amount of ultraviolet absorber for 10 o heavy duty parts,
It is 0.3 to 2.0 parts by weight, preferably 0.5 to 1.
5 parts by weight. If the amount is less than 0.3 parts by weight, the ultraviolet shielding effect will not be sufficient and the effect on useful plants will be low. Moreover, if it exceeds 2.0 parts by weight, the effect of reducing bleed-out cannot be sufficiently obtained. The total amount of ultraviolet absorber used in the film is A PHR (L -LDPE 100
If the thickness of the film (per mold cylinder part) is Bμ, then A,
In a preferred embodiment, B has the following relationship.

0.3≦A≦2.0.15≦B≦75.15≦AB≦1
50 more preferably 0.5≦A≦1.5.15≦B≦7
5.20≦AB≦120.

In addition, in embodiments in which two or more types of ultraviolet absorbers are used in combination, for example, 2-(2'-hydroxy-315'-ditasha I
J -7'tylphenyl)-5-chlorobenzotriazole (III) and 2-(2-hydroxy-3-tert-butyl-5'-methylphenyl)-5-chloropenzotriazole (fill) in combination In this case, the ratio of compound (III)/compound (1111) added is preferably 0.25 to 4.0. Still using UV absorber 3
In an embodiment in which more than one species is used in combination, for example, 2-(2-hydroxy-3-5-ditertiarybutylphenyl)-5-1
0 lobensotriazole (III),! = 2-(2
-Hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole and 2-
Compound III when used in combination with (2'-hydroxy-5'-methylphenyl)benzotriazole (V)
The ratio of / amount of compound / amount of compound (■) added is preferably 0.4.
/ 0.3 / 0.3~0.5 / 0.310.
It is 2.

The ultraviolet-shielding agricultural film of the present invention may also contain conventional additives, such as lubricants, monomerization inhibitors, antistatic agents, heat stabilizers, colorants (pigments, dyes), and flame retardants, if necessary. etc. can also be blended.

Examples of lubricants include ethylene bisstearylamide, butyl stearate paraffin wax, low molecular weight polyethylene, montanic acid lux, stearic acid, and stearyl alcohol, and examples of antioxidants include:
For example, 2,6-tert-butyl-4-methylphenol, 2,4.6-)tert-j-methylphenol, 2,2-methylenebis(4-methyl-6-tert)
t-butylphenol), 4,4'-thiobis-(3-
Examples include methyl-6-tert-butylphenol), phenyl α-naphthylamine, and the like.

Further, as antistatic agents, for example, polyoxyethylene alkylamides, alkylolamides, ethanolamides, alkyl phosphates, alkyl sulfates, etc. can be used, and as heat stabilizers, for example, dibutyl tin maleate, dibutyl tin dilaurate, stearate, etc. can be used. Calcium phosphate, zinc ricinoleate, triphenyl phosphite, etc. are suitable.

Examples of colorants that can be blended include phthalocyanine blue, phthalocyanine green, titanium oxide, chromothal red, and syncasia red.

In addition, flame retardants such as antimony oxide, aluminum hydroxide, and halogen-containing phosphoric acid esters may also be blended as appropriate.Furthermore, in order to impart antifogging properties to the ultraviolet-shielding agricultural film used in the present invention, Examples of surfactants that may be used before activation and are added to enhance antifogging properties include CallyI? Anionic surfactants such as phosphate salts, sulfonate salts, sulfuric acid ester salts, and phosphoric acid ester salts; cationic surfactants such as aliphatic amine salts, their quaternary ammonium salts, aromatic quaternary ammonium salts, etc. Active agents: Ampholytic surfactants such as betaine, aminocarboxylic acid salts, imidazolidine derivatives; Alkyl and alkylaryl polyoxyethylene ethers and their polyoxyethylene ethers, polyoxyethylene fatty acid esters, glycerin estenopesorbitan esters, polyesters, etc. Glycerin ester, dihydric alcohol ester, sucrose ester, polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitan ester, ester of nlubitol polyoxyethylene ether, ether of chrycerin ester, sorbitol polyoxyethylene ether Nonionic surfactants such as esters of oxypropylene, esters of polyoxyethylene polyoxypropylene, and esters of glycerin polyoxyethylene polyoxypropylene; fluorine surfactants; silicone surfactants, etc. These may be used alone or in combination of two or more, and the amount used can be within the range of 0.5 to 3.0 parts by weight per 100 parts by weight of general vinyl chloride resin. Among the surfactants, nonionic surfactants are suitable, in particular the following may be mentioned: sorbitan fatty acid esters, such as sorbitan monostearate, sorbitan monopalmitate; diglycerol mono(lumitate, diglycerin fatty acid esters such as diglycerin monostearate; glycerin fatty acid esters such as glycerin monostearate; pentaerythritol fatty acid esters such as bentaerymeritol monostearate; dipentaerythritol fatty acid esters such as dipentaerythritol monopalmitate; Sorbitan and diglycerin fatty acid ψ dihydrochloric acid esters such as sorbitan monopalmitate/half adipate, diglycerin monostearate/half glutamic acid ester; and condensates of these with alkylene oxides such as ethylene oxide, propylene oxide, etc., such as polyesters. Oxyethylene (2 moles) sorbitan monostearate, polyoxyethylene (2 moles) diglycerin monopalmitate, etc.; polyoxyethylene fatty alcohols such as polyoxyethylene lauryl ether; polyoxyethylene fatty acids such as polyoxyethylene monostearate Examples include esters.

The agricultural film of the present invention can be easily produced using various methods known per se, such as melt T-die extrusion and inflation extrusion.

Furthermore, the coating material of the present invention may be laminated on other synthetic resin films or sheets, glass, etc. for the purpose of reinforcement, etc., if necessary. Thus, the ultraviolet-shielding agricultural film of the present invention has extremely excellent weather resistance, can maintain excellent ultraviolet-shielding ability for a long time despite changes in outdoor weather, and can prevent bleaching. It is a strong film that maintains impact resistance, dust resistance, and tear strength over a long period of time, and is extremely useful in agricultural fields such as mulch cultivation, tunnel cultivation, and lining of greenhouse cultivation. It's a dog.

Next, the present invention will be explained in more detail with reference to examples.
, MI2. O1 density 0.922f/2J) 100 parts by weight and ultraviolet absorber 2 (2'-hydroxy-3'-t
-butyl-5-methylphenyl) 5-chlorotriazole (Japan Ciba Geigy ■, Tinuvin 326) 0.4 parts by weight and 2(2'-hydroxy-3',5'-di-t-)
T
- In the die extruder, cylinder temperature CI ~ c, 190
~195℃, die temperature -D, 220℃, 30
A film of μ was obtained. The test results are shown in Table 111.

[Examples 2 to 11 and Comparative Examples 1 to 6] In exactly the same manner as in Example 1, predetermined amounts of the resins and ultraviolet absorbers listed in Table 111 were mixed, and a 30μ film was produced using a T-die extruder. I got it. The test results are shown in Table 1. As a comparative example of low density polyethylene (LDPE), F-141 (IVII 4. O1 density 0.921) manufactured by Showa Denko ■ was used.

〔Evaluation methods〕

■. The whitening film sample was suspended in a constant temperature and humidity chamber adjusted to a temperature of 50° C. and a relative humidity of 50° C., and a surface blow-out test (whitening test) was conducted continuously for two weeks.

To judge whitening, take out the film, observe its appearance, add it, and when the ultraviolet absorber blows out white on the surface and crystallizes, it is judged as C, and when there is no change compared to the time of manufacture, it is judged as A.

2. W-0-M The film sample was subjected to a weather resistance test using a Sunshine Weather-O-Mer (W-O-M) manufactured by Suga Test Instruments Manufacturing Co., Ltd. at a sysbrae cycle of 18 minutes/12 o minutes. Below 'A-1
After the time shown in the table, remove the film and place it in a
Measure the degree of haze (ratio of scattered light dose to total transmitted light dose, haze %) f! using a manufactured haze meter. : Measured and the results are shown in Table 1. Furthermore, the whitening state of the film after 200 hours of W-0-M was visually evaluated as follows, and the results are listed in Table 1.

Evaluation of visual indication A: Almost no bleaching B: Some bleaching C: Extremely large bleaching Reference example Daikon cultivation example Magnesium lime in mid-March: 120 kf/ 10
A and low-grade chemical fertilizer 90]y/10a were uniformly spread as base fertilizer, and the furrow rl]120 on, length 20m was spread 3 times.
Making ridges, using mulching films prepared in Examples for each part, Example 2 (Film No. 2), Example 4 (Film No. 4), and commercially available polyethylene mulching film [Film No. 12, Mitsui Nopoly, thickness 30μ, Miyu] In early April, radish seeds (variety: Nagakoharu Makimi, early maturing) were sown in a staggered manner with a plant spacing of 35 crn and a row spacing of 30 m, at 3 to 5 seeds per hole. After that, in late April, when the tree germinates and has 2 to 3 leaves,
The plants were thinned out to a single tree, and immediately the roots were lightly filled with soil by hand, and cultivation was managed according to conventional methods. Harvesting was carried out from late May to early June, and the results of the yield survey are shown in Table 2.

Table 2 (g) Yield index: Calculated based on the total weight of 50 harvested daikon radish plants selected at random, with reference comparison plots set as 100.

[Brief explanation of drawings]

FIG. 1 is a wavelength-specific light transmission curve of the film used in the examples.

Claims (1)

[Claims] 1. Contains 0.3 to 2.01 parts by weight of an ultraviolet absorber consisting of a benzotriazole derivative of the following formula (1) or at least 290 to 40 parts by weight per 100 parts by weight of linear low density polyethylene.
1. An ultraviolet-shielding agricultural film having an absorption maximum in a wavelength range of up to 0 nm, and having a light shielding rate of 60% or more at the absorption maximum. 2. Having an absorption maximum in the wavelength range of at least 290 to 400nrn'j, and substantially blocking light at the absorption maximum, and substantially transmitting visible light in the wavelength range of 500nm and above. The ultraviolet-shielding agricultural film according to claim 1, characterized in that: 3. Any one of claims 1 to 2 in which the benzotriazole derivatives are two or more types! UV-shielding agricultural film as described. 4. Anchor; Species benzo)IJ azole derivatives are 2-(2'
-Hydroxy-3-5'-tert-butylphenyl)5-chlorobenztriazole and -2-(2-hydroxy-3-tert-butylphenyl)5
-Claim 3 which is chlorobenztriazole
The ultraviolet-shielding agricultural film described in Section 1. 5. The two benzo) IJ azole derivatives are 2-(2
'-Hydroxy-3-5'-ditardyarifthylphenyl) 5-riobensotriazole OIJ] and 2-(
2'-Hydroxy-3'-tert-butyl-57-methylphenyl)5-chlorobenzotriazole Qill
), and the blending weight ratio of benzotriazole derivative 011: ]/benzotriazole fatty conductor 01 old is 1/4 to
4. The ultraviolet gland-shielding agricultural film according to claim 4. 6. Claims 1 and 2, wherein the ultraviolet absorber comprises at least one benzotriazole derivative and two or more of a benzophenone ultraviolet absorber or a benzotriazole ultraviolet absorber other than the above. Ultraviolet ray blocking film for professional use. 7. The ultraviolet-shielding film for blindfolding according to claims 1 and 2, wherein the benzotriazole derivatives are three or more types. 8. The thickness of the ultraviolet-shielding agricultural film is 20 to 50
The ultraviolet-shielding agricultural film according to any one of claims 1 to 7, which is μ. -I 9. The mulching film according to claim 8, wherein the ultraviolet-shielding agricultural film is an ultraviolet-shielding mulching film.