JP2003289727A - Ultraviolet-screening polyolefin multilayer film for agriculture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet-screening polyolefin resin multilayer film for agriculture excellent in tone when being formed into a film, the sustained retention capacity of ultraviolet-screening property and weather resistance for a long period. <P>SOLUTION: This ultraviolet-screening polyolefin multilayer film for agriculture contains 0.05-1 wt.% of a hindered amine weather-resistant agent in all the layers and a benzotriazole ultraviolet absorber in the middle layer. The result of the relation, [(the rate of content of the ultraviolet absorber in the middle layer)/(the rate of content of the ultraviolet absorber in all the layers)] is ≥140%. The film does not substantially transmit at least ultraviolet of wavelength of ≤370 nm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a UV-shielding agricultural multilayer film. More specifically, the present invention relates to a UV-shielding agricultural polyolefin resin multilayer film excellent in hue when formed into a film, long-term retention of UV shielding ability, and long-term weather resistance.

[0002]

2. Description of the Related Art In recent years, in order to enhance the marketability and productivity of forcible or restrained cultivation of agricultural products, a special product mainly composed of vinyl chloride film for agriculture, polyethylene, ethylene-vinyl acetate copolymer and polyolefin resin is used. So-called greenhouse cultivation and tunnel cultivation, in which useful plants are cultivated under the covering with an agricultural covering material such as a film, are actively performed. Among them, the special film mainly composed of polyolefin resin is lighter in density because it is smaller than vinyl chloride resin and has a chemically stable structure, so its mechanical properties hardly change even during long-term use. Since it does not generate harmful gas even if it is incinerated, and furthermore, the wide film that does not require the adhesive processing for the width joint can be provided at low cost by the inflation molding method, it has been widely used. .

Various studies have been conducted on the relationship between the cultivation environment of crops and light quality, and the relationship between the cultivation environment of crops and ultraviolet rays has also been studied. For example, rice blast fungus and sesame leaf blight fungus; eggplant, tomato, cucumber, strawberry,
Watermelon, melon, pepper, lettuce, Chinese cabbage, carrot,
370, because there is a close relationship between fungal propagation such as burdock and radish on various vegetables; mold growth such as Potritis cinerea, anthracnose fungus, vine wilt fungus, black mold fungus, spot fungus, and UV wavelength. It has been reported that the growth of such molds is prevented under the complete shielding condition of ultraviolet rays having a wavelength of ˜380 nm or less.

With regard to the influence of ultraviolet rays on the cultivation environment of agricultural products and the effect of ultraviolet rays, a certain specific benzotriazole type ultraviolet absorber has been contained as an agricultural film for controlling the propagation of molds of plant diseases as described above. A vinyl chloride resin film capable of substantially completely blocking transmission of ultraviolet rays having a wavelength of 380 nm or less has been proposed (Japanese Patent Publication No. 53-47383). In the past, with regard to the cultivation environment of crops and the effects of ultraviolet rays, ultraviolet rays not only affect the reproduction of plant disease molds, but also have a great influence on the growth of crops and the quality of harvested crops. Agricultural film that can be stopped and that substantially blocks transmission of ultraviolet rays having a wavelength of 370 nm or less is used to prevent fruit cracking of tomatoes that are cultivated in a facility under clothes of such an agricultural film, and stand-up cultivation of chive, chives, etc. It has been found and proposed that the heading of lettuce or Chinese cabbage should be accelerated and the heading rate should be increased, the sugar content of fruits should be increased, and the cap of bell peppers should be aged (Japanese Patent Publication No. 55-12208). Publication, JP-B-55-10203, JP-B-56-4
6375, Japanese Patent Publication No. 57-59725, etc.).

[0005]

By the way, in order to obtain such an ultraviolet-shielding agricultural film, it is necessary to contain a considerably large amount of an ultraviolet absorber in the film.
When a large amount of this ultraviolet absorber is used, the film is colored and the commercial value is reduced. In addition, in the case of polyolefin-based resins, which are often used alongside polyvinyl chloride resins as agricultural film materials, in recent years, long-term (1 year-
Since the number of cases where it is used over 5 years is increasing, it is desirable to keep the ultraviolet shielding ability as it is during the period of use. However, this large amount of ultraviolet absorber is gradually applied to the surface. There is a problem that bleeding out causes a decrease in light transmittance due to whitening, a decrease in ultraviolet absorbing ability, and a decrease in weather resistance.

[0006]

Means for Solving the Problems The inventors of the present invention have made earnest studies to develop an ultraviolet ray-shielding agricultural polyolefin-based multilayer film which overcomes the above-mentioned drawbacks and does not cause such a problem. As a result, the agricultural polyolefin-based multilayer film has been obtained. In, containing a hindered amine-based weathering agent in all layers, further,
By containing a benzotriazole-based ultraviolet absorber in a specific layer and an ultraviolet absorber in a specific ratio in the intermediate layer, coloring when a film is formed is small, and ultraviolet rays with a wavelength of 370 nm or less are highly enhanced. Shielding, and without bleaching even under severe weather conditions in the summer, found that it is possible to obtain an agricultural polyolefin-based multi-layer film capable of continuously maintaining its high ultraviolet shielding ability for a long period of time, the present invention, It came to completion.

That is, according to the present invention, in the multilayer film for agriculture, the content of the hindered amine weathering agent contained in all layers is 0.05 to 1% by weight, and the intermediate layer further comprises a benzotriazole ultraviolet absorber. And (UV content in intermediate layer / UV absorber content in all layers) is 14
Provided is an ultraviolet ray-shielding agricultural polyolefin-based multilayer film, which is characterized in that it is substantially 0% or more and does not substantially transmit ultraviolet rays having a wavelength of at least 370 nm or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The ultraviolet-shielding agricultural polyolefin-based multilayer film of the present invention has a layer structure of at least three layers, and when the film of the present invention is spread and used in an actual house or tunnel, the layer provided in the center thereof is an intermediate layer. The inner and outer layers refer to the inner layer (the inner surface) and the outer layer (the outer surface).

The hindered amine weathering agent used in the present invention preferably has a molecular weight of 250 or more,
It is a 2,2,6,6-tetraalkylpiperidine derivative having a substituent at the 4-position, and examples of the substituent at the 4-position include a carboxylic acid residue, an alkoxy group and an alkylamino group. An alkyl group may be substituted at the N-position. Examples of the hindered amine compound usable in the present invention include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate [molecular weight: 48
1], decanedioic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester,
Reaction product of 1,1-dimethylethylhydroxyloxide and octane [molecular weight: 737], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1
-Polymer of piperidine ethanol [Molecular weight: 3100 to 3100]
4000], poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-
Diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] [molecular weight: 2000
~ 3100], dibutylamine 1,3,5-triazine N, N'-bis (2,2,6,6-tetramethyl-4
-Piperidyl-1,6-hexamethylenediamine / N-
Examples include polycondensates of (2,2,6,6-tetramethyl-4-piperidyl) butylamine [molecular weight: 2600 to 3400]. These hindered amine light stabilizers can be used alone or in combination of two or more kinds. The content thereof is 0.05 to 1% by weight, preferably 0.1 to 0.7% by weight in the whole layer. Content is 0.05
If it is less than%, sufficient weather resistance cannot be obtained for long-term annual use. On the other hand, if the content is 1% by weight or more, bleeding out occurs on the film surface, and the light transmittance decreases due to whitening, which is not preferable.

Examples of the UV absorber used in the present invention include benzotriazole UV absorbers, benzophenone UV absorbers and triazine UV absorbers.

Examples of the benzotriazole type ultraviolet absorber include 2- (2'-hydroxy-5'-methylphenyl)-
5-butoxycarbonylbenzotriazole, 2-
(2'-hydroxy-5'-methylphenyl) -5,6-
Dichlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -5-ethylsulfobenzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) -5-chlorobenzotriazole, 2-
(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-
Dimethylphenyl) benzotriazole, 2- (2'-
Hydroxy-3 ', 5'-dimethylphenyl) -5-methoxybenzotriazole, 2- (2'-methyl-4'-hydroxyphenyl) benzotriazole, 2- (2'-
Stearyloxy-3 ', 5'-dimethylphenyl) -5
-Methylbenzotriazole, 2- (2'-hydroxy-5'-ethoxycarbonylphenyl) benzotriazole, 2- (2'-hydroxy-3'-methyl-5'-ter
t-butylphenyl) benzotriazole, 2- (2'-
Hydroxy-5′-methoxyphenyl) benzotriazole, 2- (2′-hydroxy-5′-phenylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-cyclohexylphenyl) benzotriazole, 2- (2'-hydroxy-4 ', 5'-dimethylphenyl) -5-butoxycarbonylbenzotriazole, 2- (2'-hydroxy-3', 5'-dichlorophenyl) benzotriazole, 2- (2 ' -Hydroxy-
4 ', 5'-dichlorophenyl) benzotriazole, 2
-(2'-hydroxy-3 ', 5'-dimethylphenyl)
-5-ethylsulfobenzotriazole, 2- (2'-
Hydroxy-5′-phenylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2- (2′-hydroxy-5 ′)
-Methoxyphenyl) -5-methylbenzotriazole, 2- (2'-hydroxy-5'-methylphenyl)-
5-ethoxycarbonylbenzotriazole, 2-
(2'-acetoxy-5'-methylphenyl) benzotriazole may be mentioned.

Among these UV absorbers, the preferred UV absorber is represented by the following formula:

[Chemical 1] [Wherein R ₁ and R ₂ are the same or different and each represents a hydrogen atom, a lower alkyl group, particularly a branched lower alkyl group, or an aryl group, especially a phenyl group, and X is a hydrogen atom or a halogen atom. , Especially a chlorine atom].

As the benzophenone type ultraviolet absorber,
2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-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'-tetrahydroxybenzophenone, 2,2'-hydroxy-4,4'-dimethoxy-5-sodium sulfobenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-5-chlorobenzophenone, etc. Can be mentioned. As a triazine-based ultraviolet absorber, 2- (4,
6-diphenyl-1,3,5-triazin-2-yl)
-5-[(hexyl) oxy] -phenol, 2-
[4,6-bis (2,4-dimethylphenyl) -1,
3,5-triazin-2-yl] -5- (octyloxy) phenol, and triazines such as triaryltriazines such as UV1164 (manufactured by Cytec) and TINUVIN 1577 FF (manufactured by Ciba Specialty Chemicals). These ultraviolet absorbers are used alone or in combination of two or more.

The amount of the ultraviolet absorber as described above is such that the film formed from the resin composition containing the ultraviolet absorber does not substantially transmit ultraviolet rays having a wavelength of at least 370 nm or less, preferably 380 nm or less. Contained in. Here, "substantially not transmitting ultraviolet rays having a wavelength of X nm or less" means not only completely transmitting ultraviolet rays having a wavelength of X nm or less (transmittance 0%), but also transmittance of ultraviolet rays having a wavelength of X nm or less. Is less than or equal to 5%, preferably less than or equal to 3%, which means that some transmission of ultraviolet rays having the wavelength is allowed. The content of the above-mentioned UV absorber for achieving such UV-shielding property cannot be unconditionally determined because it is related to the UV-absorption characteristics of the individual UV-absorbers used, the thickness of the film, etc. As a guideline, the content of UV absorber (A) [content with respect to polyolefin resin (% by weight)] and film thickness (B)
The product (AB) with [unit: micron] is generally 20 to 15
0, preferably 30 to 140, more preferably 35
It is suitable to be in the range of 130.
Further, if the content of the ultraviolet absorber becomes too large, it may cause spouting and the like. Therefore, the upper limit of the content of the ultraviolet absorber in the polyolefin resin is generally 3% by weight or less, preferably 2% by weight or less. Is desirable. The lower limit of the content of each ultraviolet absorber is 0.01% by weight or more,
It is desirable that the amount is preferably 0.05% by weight or more. A more specific content can be easily determined by those skilled in the art by experimentally forming a film for each ultraviolet absorber and measuring its light transmission characteristics.

The benzotriazole UV absorber used in the multilayer film of the present invention must be contained in at least the intermediate layer. The other ultraviolet absorber may be contained in any layer, but is preferably contained in other than the intermediate layer. Therefore, it is preferably 80% or more, more preferably 9% of the ultraviolet absorber contained in the intermediate layer.
5% or more is a benzotriazole type ultraviolet absorber. In addition, the ultraviolet absorber content of (UV content in intermediate layer / UV content in all layers) is 140%.
It is necessary to be above. It is preferably 145% or more, more preferably 150% or more, and the upper limit is preferably 500% or less, more preferably 300% or less. The multilayer film formed in this way has little coloring and highly shields ultraviolet rays having a wavelength of 370 nm or less, and does not whiten even under severe weather conditions in the summer, and its high ultraviolet shielding ability for a long period of time. An agricultural polyolefin-based multilayer film that can be retained for a long time is obtained.

The polyolefin resin used in the present invention is a homopolymer of α-olefin and a copolymer of α-olefin with a different kind of monomer as a main component, such as polyethylene, polypropylene and ethylene. 1-butene, 1-pentene, 1-hexene, 4-methyl-1-
Pentene, 1-octene, 1-decene, etc., 4 carbon atoms
Copolymers with α-olefins of 10 to 10, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, ethylene-methacrylic acid ester copolymers, ethylene-acetic acid Examples thereof include vinyl-methacrylic acid ester copolymers and ionomer resins. Among these resins, as a resin used for the inner and outer layers, the number of carbon atoms is 4 to 2 in the presence of a metallocene catalyst.
An ethylene-α-olefin copolymer resin obtained by copolymerizing 0-α-olefin with a liquid phase or a gas phase is particularly preferable in that the weather resistance can be maintained for a long period of time.

As the resin used for the intermediate layer, an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 5% by weight to 25% by weight is particularly preferable because it is excellent in transparency, flexibility and heat retention. These resins may be used alone or in combination of two or more. The melt flow rate (MFR) of the above polyolefin resin is JIS-
The measurement method according to K6760 is 0.1 to 10 g / 10 minutes, preferably 0.2 to 5 g / 10 minutes, more preferably 0.5.
It is in the range of up to 5 g / 10 minutes. If the MFR is larger than this range, the film will meander during inflation molding and the end portions of the wound film will be uneven, resulting in poor molding stability. Further, if the MFR is smaller than this range, the load on the molding machine increases, and therefore it is necessary to reduce the production rate to suppress the increase in pressure, resulting in a marked decrease in productivity and impracticality. The density of the polyethylene or ethylene-α-olefin copolymer is in the range of 0.905 to 0.925 g / cm 3, more preferably 0.910 to 0.925 g / cm 3 as measured by JIS-K6760. When the density is higher than this range, the transparency of the film is deteriorated and the tear strength in the machine direction is also decreased. On the other hand, if the density is lower than this range, blocking occurs due to stickiness of the film surface, and the opening property during the work of spreading on the house is significantly deteriorated, which is not practical.

The resin composition constituting the intermediate layer, the inner layer and the outer layer in the present invention is an antifogging agent, an antifog agent, an antioxidant, a lubricant or a heat stabilizer as long as the above-mentioned resin is not impaired. , Various additives such as anti-blocking agent, ultraviolet absorber, weathering agent, colorant, antistatic agent, etc. can be added.

As the antifogging agent to be added for the purpose of imparting antifogging property, a general one usually added to an agricultural film can be used. Specifically, for example, lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol monopalmitate, polyethylene glycol monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monoether. Palmitate, glycerin monolaurate, glycerin monopalmitate, glycerin monostearate, glycerin monooleate, pentaerythritol monolaurate, sorbitan monopalmitate, sorbitan monobehenate, sorbitan distearate, diglycerin monooleate, Triglycerindiolate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium butylnaphthalene sulfonate , Cetyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, dodecylamine hydrochloride, lauric acid laurylamide ethyl phosphate, triethylcetylammonium iodide, oleylaminodiethylamine hydrochloride, basic pyridinium salt of dodecylpyridinium sulfate, etc. To be Of these, preferred are fatty acids having 14 to 22 carbon atoms, sorbitan, sorbitol, glycerin, polyglycerin,
Examples thereof include nonionic surfactants whose main component is an ester with a polyhydric alcohol such as propylene glycol or an alkylene oxide adduct thereof. These surfactants can be used alone or in combination of two or more. The content is 0.
1 to 5% by weight, particularly 0.3 to 3% by weight is preferable. 0.
If it is less than 1% by weight, sufficient antifogging property cannot be obtained, and if it exceeds 5% by weight, a large amount of it is spouted onto the film surface and transparency is impaired, which is not preferable. As a method of maintaining the antifogging property of the multilayer film for a long period of time, other than the method of incorporating the above-described antifogging agent into the film, an antifogging film is formed on the innermost layer of the multilayer film spread on an agricultural house or the like. There is a method of making it. Examples of such an antifogging coating include an inorganic colloid sol such as silica sol and / or alumina sol, a composition containing a binder resin such as a thermoplastic resin as a main component, and the like.

Examples of the antifogging agent include fluorine-containing surfactants having a perfluoroalkyl group, ω-hydrofluoroalkyl group and the like, and silicone-containing surfactants having an alkylsiloxane group. The blending amount is 0.01 to 2% by weight with respect to the polyolefin resin, and preferably,
It is 0.02-1% by weight. Specific fluorine-containing surfactants include Unidyne DS403 manufactured by Daikin Industries,
Examples thereof include DS406 and DS401.

Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,2-methylenebis (6-t-butyl-4-ethylphenol), dilaurylthiodipropionate and the like. Hindered phenolic,
Examples thereof include phosphorus type and sulfur type. These antioxidants can be used alone or in combination of two or more, and usually 0.01 to 0.5% by weight is preferable.

Examples of lubricants or heat stabilizers include polyethylene wax, liquid paraffin, aliphatic alcohol, stearic acid, lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, zinc stearate, and stearate. Calcium phosphate, magnesium stearate, barium stearate, barium ricinoleate, dibutyltin dimaleate, organic phosphate metal salt, organic phosphate compound,
Examples thereof include organic phosphite compounds, phenols, β-diketone compounds and the like. These lubricants or heat stabilizers can be used alone or in combination of two or more, and usually in the range of 0.01 to 0.5% by weight is preferable.

As the anti-blocking agent, diatomaceous earth,
Examples thereof include synthetic silica, talc, mica, zeolite and the like. These antiblocking agents can be used alone or in combination of two or more, and are usually 0.01 to
A range of 0.5% by weight is preferred.

Inorganic compounds are added to the agricultural multilayer film of the present invention for the purpose of improving the heat retention of the film. Inorganic compounds effective as heat retaining agents include Mg and C
Examples thereof include inorganic oxides and inorganic hydroxides containing at least one atom of a, Zn, Al, Si and Li. Specifically, magnesium oxide, calcium oxide, aluminum oxide silicon oxide, titanium oxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, potassium sulfate, magnesium sulfate, calcium sulfate, Zinc sulfate, aluminum sulfate, lithium phosphate, sodium phosphate, potassium phosphate, calcium phosphate, magnesium silicate, calcium silicate, aluminum silicate, titanium silicate,
Sodium aluminate, potassium aluminate, calcium aluminate, sodium aluminosilicate, potassium aluminosilicate, calcium aluminosilicate, kaolin,
Talc, mica, clay, hydrotalcite compounds, lithium-aluminum composite hydroxide, lithium
Aluminum-magnesium complex carbonate compound, lithium-aluminum-magnesium complex silicate compound,
Aluminum-magnesium-silicon composite hydroxide, aluminum-magnesium-silicon composite carbonate compound,
Aluminum-magnesium-silicon composite sulfate compound, chalcoalumite compound and the like can be mentioned. Among these, hydrotalcite compounds are preferable from the viewpoint of dispersibility in resin, transparency and heat retention. When an inorganic compound is used in the present invention, its content is 0.1 to 25% by weight, preferably 1 to 20% by weight, based on the polyolefin resin. The above inorganic compounds can be used alone or in combination of two or more.
The average particle size is in the range of 0.05 to 10 μm, more preferably 0.1 to 5 μm. If the average particle size of the inorganic fine particles is smaller than the above range, the dispersibility in the resin is poor and the particles (secondary agglomerates) are formed to deteriorate the film appearance. Poor in practical use and poor in practicality. On the other hand, if the average particle size of the inorganic fine particles is larger than the above range, the transparency is inferior, and the breaker screen of the extruder is clogged to lower the productivity, which is not preferable. Further, as a preferable mode of the heat retaining agent used in the present invention, there is a mode in which the inorganic compound having the heat retaining effect is contained only in the intermediate layer.

In order to add various additives to the multilayer film of the present invention, necessary amounts of the additives are added to each of them, and a ribbon blender, a pressure kneader, a Banbury mixer, a super mixer and other conventionally known compounding machines, mixers and kneaders. You can use the machine. The resin composition thus obtained can be formed into a film as a multilayer film by a method known per se, for example, a melt coextrusion molding method (including a T die method and an inflation method), a calender molding method, a laminating method, etc. The method known from the above can be used. Among these, the air-cooled inflation coextrusion molding method is particularly preferable in that a wide film suitable for agriculture can be obtained.

The thickness of the layers constituting the outer layer and the inner layer in the present invention is preferably 5 to 50 μm. If it is less than 5 μm, the strength is not substantially improved, and if it exceeds 50 μm, the film becomes hard and the workability for spreading on the house and the hermeticity of the house are insufficient, and the heat retention is deteriorated, which is not preferable.

The thickness of the agricultural polyolefin-based multilayer film of the present invention is 30 to 30 in terms of strength and cost.
The range of 0 μm is preferable, and the range of 50 to 200 μm is more preferable.

The layer ratio of the three-layer film of the present invention is 1/0.
The range of 5/1 to 1/5/1 is preferable, and 1/2/1 to 1
The range of / 4/1 is more preferable. Further, the ratio of the outer layer to the inner layer is not particularly specified, but it is preferable to set the same ratio in view of the curl property of the obtained film.

[0029]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. (1) Preparation of multi-layer film As a three-layer inflation molding device, 100 for three-layer die
Using a die of mmΦ, the extruder has a tube inner / outer layer of 30 m
2 mΦ extruders, 40 mmΦ middle layer extruder, inner and outer layer extruder temperature 180 ° C., middle layer extruder temperature 18
100 m roll of tubular three-layer film composed of the components shown in Table-1 and Table-2 at 0 ° C, die temperature 190 ° C, blow ratio 3.0, take-up speed 4m / min, thickness 0.10mm. Obtained. Since these films are used by cutting one end of the tube open when the house is expanded, the inner layer of the tube during film formation becomes the outer layer (outer surface) of the house when the film is expanded.

Each of the obtained multilayer film samples was subjected to the following measurement and evaluation. The results are shown in Table-1 and Table-2. Film Hue The hue of the multilayer film obtained by three-layer inflation molding was visually evaluated according to the following criteria. ◯: Almost no yellow color Δ: Yellow color X: Yellow color is remarkable The total light transmittance at 370 nm of the multilayer film was measured by an ultraviolet shielding spectrophotometer. UV protection Persistence A pipe house with a height of 1.5 m, a frontage of 2 m, and a depth of 5 m was constructed in a field in Isshi-gun, Mie Prefecture, and 3 film samples were constructed.
After stretching for one year, sampling was performed, dust on the surface was removed by washing with water, and the total light transmittance of the film at 370 nm was measured by a spectrophotometer. Film whitening property The whitening state of the film spread in the above house for 3 years was visually observed and evaluated according to the following criteria. ◯: Almost no whitening △: Whitening extremely: Whitening Extremely high weather resistance A film stretched in the above house for 3 years was sampled and the tensile elongation at break at a measuring temperature of 23 ° C. was measured according to the measuring method of JIS-K6783. The flow direction (length) of the film was measured. Similarly, the tensile elongation at break of the origin (unstretched) film was measured, and the tensile elongation at break / strength of the stretched film / value of the origin film was expressed as a percentage in the table as the weather resistance retention rate.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

The ultraviolet ray-shielding agricultural polyolefin-based multilayer film of the present invention has a hue when the film is formed,
It is extremely excellent in various properties such as long-term retention of ultraviolet ray shielding ability and long-term weather resistance, and is extremely useful as a covering material for agriculture.

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[Procedure amendment]

[Submission date] May 22, 2002 (2002.5.2)
2)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

That is, according to the present invention, in the multilayer film for agriculture, the content of the hindered amine weathering agent contained in all layers is 0.05 to 1% by weight, and the intermediate layer further comprises a benzotriazole ultraviolet absorber. Including (UV absorber content in the intermediate layer / UV absorber content in all layers)
Is 140% or more and does not substantially transmit ultraviolet rays having a wavelength of at least 370 nm or less, and an ultraviolet ray-shielding agricultural polyolefin-based multilayer film is provided.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The benzotriazole UV absorber used in the multilayer film of the present invention must be contained in at least the intermediate layer. The other ultraviolet absorber may be contained in any layer, but is preferably contained in other than the intermediate layer. Therefore, it is preferably 80% or more, more preferably 9% of the ultraviolet absorber contained in the intermediate layer.
5% or more is a benzotriazole type ultraviolet absorber. Further, it is necessary that the UV absorber content of (ultraviolet absorbing agent content in the intermediate layer / UV absorber content of all the layers in) is 140% or more. It is preferably 145% or more, more preferably 150% or more, and the upper limit is preferably 500% or less, more preferably 300% or less. The multilayer film formed in this way has little coloring and highly shields ultraviolet rays having a wavelength of 370 nm or less, and does not whiten even under severe weather conditions in the summer, and its high ultraviolet shielding ability for a long period of time. An agricultural polyolefin-based multilayer film that can be retained for a long time is obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuya Kinoshita             2 Oike, Iwatsuka-cho, Nakamura-ku, Nagoya-shi, Aichi             Mitsubishi Chemical MKV Co., Ltd. Nagoya             Inside the office F-term (reference) 2B024 DA05 DB01 EA01                 2B029 EB02 EC02 EC09 EC14 EC16                       EC17                 4F100 AK01B AK62B AT00A BA02                       CA07 GB01 JD09 YY00

Claims (2)

[Claims] 1. A multi-layer film for agriculture, wherein the content of hindered amine weathering agent contained in all layers is 0.05.
˜1% by weight, further containing a benzotriazole-based UV absorber in the intermediate layer, (UV content in intermediate layer / UV absorber content in all layers) is 140% or more, and at least 370 nm An ultraviolet ray-shielding agricultural polyolefin-based multilayer film, which is substantially impermeable to ultraviolet rays having the following wavelengths. 2. The ultraviolet ray-shielding agricultural polyolefin-based multilayer film according to claim 1, wherein at least one of the polyolefin-based resins for the inner and outer layers is an ethylene-α-olefin copolymer resin produced by using a metallocene catalyst. .