JPH1120090A - Agricultural polyolefin resin laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural polyolefin resin film having excellent molding stability and heat-fusing property and excellent antifogging durability. SOLUTION: The film outer layer is composed of a composition obtained by mixing 55 to 80% by weight of a branched low-density polyethylene produced by a high-pressure radical method and 45 to 20% by weight of a linear low-density polyethylene. The layer is an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 10% by weight or more, and the layer comprising a composition containing an antifogging agent and a specific inorganic compound in the resin, and the film inner layer having a vinyl acetate content of Is an ethylene-vinyl acetate copolymer resin of less than 10% by weight, and is a layer comprising a composition containing an antifogging agent in the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural polyolefin resin laminated film. More specifically, the present invention relates to a polyolefin resin laminated film for agricultural use having excellent molding stability and heat-fusing property and excellent anti-fogging durability.

[0002]

2. Description of the Related Art In recent years, in order to increase marketability and productivity of agricultural crops by semi-forcing or restraining cultivation, agricultural crops such as polyvinyl chloride film, polyethylene, ethylene-vinyl acetate copolymer, and polyolefin resin are mainly used. So-called house cultivation and tunnel cultivation, in which useful plants are cultivated under an agricultural covering material such as a special film, have been actively performed. Above all, special films mainly composed of polyolefin resin have stable chemical structure, so their light transmittance hardly changes even after long-term use, and no harmful gas is generated even when incinerated. Because of its low cost, it is becoming popular.

[0003] In recent years, houses have been increasing in size year by year, and accordingly, there has been a demand for a film having a wide width to be used as a covering material for the house. For the formation of agricultural polyolefin films, tubular films are usually manufactured by the inflation method, and when forming wide films,
There is a need for more stable molding of tubes (referred to as molding stability). In other words, if the tube is not stable during the formation of the wide film, the ends of the wound film become uneven, and a film having a constant width cannot be obtained. In addition, with the enlargement of the house, a considerable force is applied at the time of film expansion, and in that case, a high-strength film that does not tear is demanded.

Further, in order to control the temperature inside the house in accordance with a change in the outside air temperature, the operation of winding and lowering the side film of the house is repeatedly performed for a long time. When the film wound up during the day is exposed to sunlight for a long time, it is also necessary that the films do not cause heat fusion (heat-fusing property). Further, anti-fog continuity, which is mainly required for ceilings, is also required for side films that repeat such operations. The anti-fog persistence referred to here is the performance that the condensed water adhering to the inner surface of the film falls down along the inner surface of the film quickly without falling to the cultivated crops for a long time. Say that.

[0005] Concerning the anti-fogging durability, conventionally, as a method of imparting anti-fogging property to a polyolefin film in agricultural use, a method of applying a liquid anti-fogging agent or a solution containing an anti-fogging agent, or a method of applying anti-fogging agent. A method of kneading a fogging agent and the like have been proposed and have been put to practical use. For example, Japanese Patent Publication No. 63-65026 proposes an improvement in a method in which a linear polyethylene is used as a base layer and a resin compatible with the base layer and containing an antifogging agent is laminated. Also,
Japanese Patent Application Laid-Open No. 1-182037 proposes an agricultural film having antifogging durability, heat retention and toughness by adding an inorganic compound to the linear polyethylene described in the above patent.

[0006] However, although these films have excellent transparency, since all of them have a linear polyethylene as a base layer, the molding stability at the time of forming an inflation film is inferior. It was found that the anti-fogging continuity of the hoisting and lowering work portions was poor. Japanese Unexamined Patent Publication (Kokai) No. 63-149147 discloses an ethylene-vinyl acetate copolymer containing a branched low-density polyethylene produced by a high-pressure radical method as a base layer and further containing an antifogging agent and hydrotalcite. A method of laminating a united body has been proposed. However, although this film has the effect of improving the anti-fogging durability, it has been found that sufficient strength and elongation of the film cannot be obtained because the branched low-density polyethylene is used as the base layer.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have overcome the above-mentioned drawbacks, have excellent molding stability and heat-sealing resistance, and have anti-fogging continuity, transparency, heat retention and the like. For a film that satisfies all requirements, as a result of extensive investigation, a composition obtained by mixing a branched low-density polyethylene and a linear low-density polyethylene at a specific ratio is used for the outer layer portion of the laminated film,
A composition comprising a specific ethylene-vinyl acetate resin containing an antifogging agent and an inorganic compound as an intermediate layer portion,
The present inventors have found that the present invention can be achieved by forming a film of three types and three layers in which a composition composed of a specific ethylene-vinyl acetate resin containing an antifogging agent is laminated as an inner layer portion, and the present invention has been completed.

[0008]

That is, the gist of the present invention is that the outer layer of the film contains 55 to 80% by weight of a branched low-density polyethylene produced by a high-pressure radical method, and
The layer composed of a composition containing 45 to 20% by weight of linear low-density polyethylene and the film intermediate layer are ethylene-vinyl acetate copolymer resins having a vinyl acetate content of 10% by weight or more, and are protected in the resin. Clouding agent and Mg, Ca, Al, S
i) a layer comprising a composition containing an inorganic compound containing at least one atom of i, and an inner layer of the film having a vinyl acetate content of 1
It is an ethylene-vinyl acetate copolymer resin of less than 0% by weight and is a layer made of a composition containing an antifogging agent in the resin.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The agricultural polyolefin resin laminated film of the present invention,
An outer layer, an intermediate layer, and an inner layer.When the film of the present invention is actually stretched and used, the outer surface of a house, a tunnel, or the like is an outer layer, the inner surface is an inner layer, and a layer in between them is an inner layer. It is called an intermediate layer.

In the present invention, one component constituting the outer layer is
Polyethylene Produced by High Pressure Radical Process Used
Tylene generally means a polymerization pressure of 1000 to 3500 kg /
cm ^TwoAt a reaction temperature of 200 to 350 ° C.
Polyester obtained by reacting a Nomer with a catalyst
Tylene, having a density of 0.91 to 0.93 g / cm^Threeof
A thing. Melt flow rate (MFR: JISK6
760) is 0.3 to 3 g / 10 min.
Are preferred. If the MFR is less than 0.3
Extrusion and high-speed moldability deteriorate during film formation
Is not preferred. In addition, if it is 3 or more, inflation
During molding, the tube becomes unstable and the winding
The ends of the lum are uneven and molding stability is poor.
Not good.

The linear low-density polyethylene used as the other mixed component constituting the outer layer in the present invention is commonly called L-LDPE, and is composed of ethylene and propylene, butene-1, hexene-1,4- It is a copolymer with α-olefin such as methylpentene-1 and octene. The copolymer is produced by copolymerizing in a liquid phase or a gas phase in the presence of a Ziegler catalyst, a chromium oxide catalyst, a molybdenum oxide catalyst, a metallocene catalyst and the like. Particularly preferred linear ethylene-α-olefin copolymers are described in JP-A-6-9724 and JP-A-6-136.
In the presence of a so-called metallocene-based olefin polymerization catalyst containing a metallocene catalyst component described in JP-A-195-195, JP-A-6-136196, JP-A-6-207057, etc., ethylene and C 3 -C 12 are present. Α
-Copolymerized with an olefin so that the resulting copolymer has a density of 0.880 to 0.940 g / cm ³ and a melt flow rate (MFR) of 0.3 to ³ g / 10 min. .

The composition used for the outer layer of the present invention comprises 55 to 80% by weight, preferably 60 to 70% by weight of the branched low-density polyethylene produced by the high-pressure radical method described above, and 60 to 70% by weight of the linear low-density polyethylene. It is a mixture of 45 to 20% by weight, preferably 40 to 30% by weight. If the content of the branched polyethylene is less than 55% by weight, the molding stability is poor, and the antifogging durability of the side film is reduced. If the content is less than 10% by weight, the strength, elongation and transparency of the film are reduced. Worsens.

The resin constituting the outer layer is preferably added with a weather resistance stabilizer, an antioxidant and the like from the viewpoint of maintaining weather resistance and heat resistance. Weather stabilizers are roughly classified into light stabilizers and ultraviolet absorbers.
For example, a hindered amine light stabilizer is preferably used. As the ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, and a salicylic acid-based ultraviolet absorber are preferably used.

For the intermediate layer of the present invention, an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 10% by weight or more is used. The vinyl acetate content is 10% by weight or more, preferably 12% by weight or more and 30% by weight or less. When an ethylene-vinyl acetate copolymer resin having a vinyl acetate content in this range is used as the intermediate layer, an agricultural film excellent in flexibility and heat retention can be obtained.

As the antifogging agent to be added to the intermediate layer of the present invention, general antifogging agents which are usually blended in agricultural films 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 monolaurate Palmitate, glycerin monolaurate, glycerin monopalmitate, glycerin monostearate, glycerin monooleate, pentaerythritol monolaurate, sorbitan monopalmitate, sorbitan monobehenate,
Sorbitan distearate, diglycerin monooleate, triglycerindiolate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate,
Basicity of sodium butylnaphthalenesulfonate, cetyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, dodecylamine hydrochloride, laurylamidoethyl laurate, triethylcetylammonium iodide, oleylaminodiethylamine hydrochloride, dodecylpyridinium sulfate And pyridinium salts. Among them, preferred are non-ionic fatty acids having 14 to 22 carbon atoms and esters of polyhydric alcohols such as sorbitan, sorbitol, glycerin, polyglycerin and propylene glycol or alkylene oxide adducts thereof. Surfactants and the like. These surfactants can be used alone or in combination of two or more.

The content is preferably 0.1 to 5 parts by weight, particularly preferably 0.3 to 3 parts by weight, per 100 parts by weight of the resin. If the amount is less than 0.1 part by weight, sufficient antifogging property cannot be obtained.

The intermediate layer of the present invention contains an inorganic compound containing at least one of Mg, Ca, Al and Si. For example, Mg, Ca, effective as a heat insulator,
Examples include inorganic oxides, inorganic hydroxides, and hydrotalcites containing at least one atom of Al and Si. Specifically, SiO ₂ , Al ₂ O ₃ , MgO, CaO
Inorganic oxides such as Al (OH) ₃ , Mg (OH) ₂ , Ca
Inorganic hydroxides such as (OH) ₂ ; formula M2 ⁺ _1- xAlx (OH)
In ^{_{2 (A n-) x / n}} · mH 2 O [ wherein, M ²⁺ is a divalent metal ion of Mg, Ca or Zn, A ^n-is Cl ^-, Br ^{chromatography,}
I ^-, NO ₃ ² over, ClO ^{4 over,} SO ₄ ^2-, CO _{² 2} chromatography, SiO _{3
^{2-, HPO 4 2-, HBO 3}} 2 ^over an anion of PO ₄ ^{2 over} like, x is a numerical value satisfying the condition of 0 <x <0.5,
m is a numerical value that satisfies the condition of 0 ≦ m ≦ 2], and hydrotalcites such as a calcined product thereof. Among these, hydrotalcites are preferable, and a fired product of the inorganic composite compound represented by the above formula is particularly preferable. The inorganic compound as described above,
They can be used alone or in combination of two or more.

The average particle size of the inorganic compound is preferably 10 μm or less, particularly preferably 5 μm or less. When the average particle size of the inorganic compound is within the above range, a laminated film having good transparency can be obtained. The content of the inorganic compound is preferably 1 to 10 parts by weight per 100 parts by weight of the resin. 1
If the amount is less than 10 parts by weight, the heat retention is insufficient.
If the amount is more than parts by weight, transparency is undesirably reduced. The intermediate layer may contain a weather resistance stabilizer, an antioxidant, and the like, if necessary, in addition to the antifogging agent and the inorganic compound.

The inner layer of the present invention has a vinyl acetate content of 1
Less than 0% by weight of an ethylene-vinyl acetate copolymer resin is used. The vinyl acetate content is less than 10% by weight, preferably 8%
% By weight. When an ethylene-vinyl acetate copolymer resin having a vinyl acetate content in this range is used as the inner layer, an agricultural film excellent in heat-sealing resistance can be obtained. As the resin constituting the inner layer, not only one kind but also a mixture of two or more kinds of resins can be used as long as the final average vinyl acetate content is less than 10% by weight.

As the antifogging agent to be added to the inner layer, the same antifogging agent as added to the above-mentioned intermediate layer can be used. These antifogging agents can be used alone or in combination of two or more. The content of the anti-fogging agent is preferably 0.1 to 5 parts by weight per 100 parts by weight of the resin. More preferably, it is 0.3 to 3 parts by weight. Content is 0.1
If the amount is less than parts by weight, sufficient antifogging property cannot be obtained. On the other hand, when the content is 5 parts by weight or more, a large amount of blowout to the film surface is caused, and transparency is impaired.

Each layer of the agricultural polyolefin resin laminated film of the present invention may contain wax, antioxidant, antistatic agent, light stabilizer, ultraviolet absorber, lubricant, antiblocking agent, antifog, A heat insulator and the like can be added. Further, the outer layer surface of the agricultural polyolefin resin laminated film of the present invention can take a form of transparent, semi-matte, or matt depending on the purpose of use.

The agricultural polyolefin resin laminated film of the present invention is prepared by weighing the required amount of the polyolefin resin and each additive used in each layer, and using a ribbon blender, a Banbury mixer, a super mixer and other compounding machines and mixers. Mix. Then, the obtained composition can be prepared by laminating the outer layer, the intermediate layer and the inner layer by a method known per se, for example, a method such as a coextrusion inflation method or a coextrusion T-die method.

The thickness of all the layers is preferably in the range of 0.04 to 0.2 mm in consideration of strength, performance, production cost and the like. The thickness of the outer layer is preferably 5 to 50 μm, and when the outer layer is less than 5 μm, the strength is substantially insufficient, and thus the film is not suitable. The thickness of each layer can be arbitrarily selected as long as the intermediate layer is thicker than the outer layer, preferably 2 to 4 times the outer layer, and the inner layer is in the same range as the outer layer.

[0024]

The agricultural polyolefin film of the present invention is excellent in all performances such as molding stability, heat sealing property, heat retention and anti-fogging durability. Extremely high.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments, but the present invention is not limited to the following examples unless it exceeds the gist. Examples 1 to 5, Comparative Examples 1 to 9

Preparation of Laminated Film As a three-layer blown film forming apparatus, a die having a diameter of 1500 mmΦ is used as a three-layer die, and two extruders each using a screw having a diameter of 100 mmΦ for the inner and outer layers and an intermediate layer having a diameter of 150 mmΦ. As the one using a screw, the temperature of the outer layer extruder is 180 ° C.
Agricultural polyolefin resin laminated film composed of the components shown in Tables 1 to 4 at 0 ° C., a die temperature of 170 ° C., a blow ratio of 2.0, a take-up speed of 10 m / min, a folded diameter of 400 cm, and a thickness of 100 μm was prepared. It was wound 100 m on an inch paper tube.

The following physical properties were measured for each of the laminated films. The respective measuring methods are shown in Tables 1-1 to 1-3. (1) Molding stability The width of irregularities at the winding end of each of the obtained films was measured on a scale to judge pass / fail. The criteria are as follows. ○: Irregular width at end less than ± 2 mm △: Irregular width at end ± 2 mm or more to less than ± 5 mm ×: Irregular width at end ± 5 mm or more

(2) Strength at Break The strength at break in the longitudinal and transverse directions of each of the obtained films was measured by a tensile test (based on JIS K6783). (3) Elongation at Break The elongation at break of the laminated film in the longitudinal and transverse directions was measured by a tensile test (based on JIS K6783). (4) Transparency The parallel light transmittance of each of the obtained films at a wavelength of 555 mm was measured by a spectrophotometer, and the value was shown.

(5) Heat insulation In a field in Isshi-gun, Mie Prefecture, a height of 1 m, a width of 2 m, and a depth of 2
A pipe house of m m was constructed, and each obtained film was spread so as to be in a sealed state. The temperature difference between the inside and outside of the house at a height of 15 cm from the ground surface was measured every hour from 7:00 in the morning to 6:00 in the next morning, and the average value was calculated. The larger the temperature difference, the better the heat retention. Measurements have been 1 since December 19, 1996
Conducted on February 20.

(6) Sustainability of anti-fogging and heat-fusing properties In the same field as above, a height of 2.5 m, a frontage of 4.5 m, and a depth of 20
An m-shaped pipe house was constructed, and each of the obtained films having a width of 2 m was inscribed in the arch direction and stretched so that the whole house was sealed. A film winding device was installed so that the side surface of the house could be ventilated for the purpose of controlling the internal temperature, and the winding and unwinding operations were repeated according to changes in temperature. The evaluation of antifogging durability was performed on the ceiling and side portions of the laminated film. As for the evaluation method, the state of water droplets adhering to the inner surface of the film being stretched was visually observed over time. The evaluation criteria are as follows (test started on September 1, 1996).

A: Water droplets adhering to the film surface (the surface facing the inside of the house, the same applies hereinafter) coalesce and spread in a thin film form, and the area of the thin film portion is 2/3 of the film surface.
What extends over. ：: Coalescence of water droplets adhering to the film surface is recognized, but the area of the thin film portion is less than 2/3 or 1/2 or more of the film surface. Δ: Coalescence of water droplets adhering to the film surface is recognized, but the shape of the thin film portion is not recognized. ×: No coalescence of water droplets adhering to the film surface is observed.

The evaluation of the heat sealability was made by evaluating the appearance one year after the film winding and winding operations were repeated. The evaluation criteria are as follows. ：: No change in film surface. ×: Traces of blocking are observed on the film surface.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

(Note) LDPE (A): branched polyethylene (MFR: density 0.92) L-LDPE (B): linear polyethylene produced by Ziegler catalyst (MFR: 0.9 density 0.924) L-LDPE (C): linear polyethylene produced with a metallocene catalyst (MFR: density 0.910) Hydrotalcite: DHT4A (manufactured by Kyowa Chemical Co., Ltd.) UV531: benzophenone ultraviolet absorber Chimassorb 944 manufactured by Scitech : Light stabilizer manufactured by Ciba-Geigy

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI B32B 27/32 103 B32B 27/32 103 (72) Inventor Atsushi Obayashi 2 Oike, Iwatsukacho, Nakamura-ku, Nagoya-shi, Aichi Nagoya Business Mitsubishi Chemical Corporation Inside

Claims (2)

[Claims] The film outer layer is composed of a composition obtained by mixing 55 to 80% by weight of a branched low-density polyethylene produced by a high-pressure radical method and 45 to 20% by weight of a linear low-density polyethylene. The intermediate layer is an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 10% by weight or more, and an antifogging agent, Mg, Ca, and A in the resin.
1, a layer comprising a composition containing an inorganic compound containing at least one atom of Si, an inner layer of the film is an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of less than 10% by weight, and an antifogging agent in the resin. A polyolefin resin laminated film for agricultural use, which is a layer comprising a composition containing: 2. The method according to claim 1, wherein the linear low-density polyethylene in the outer layer comprises ethylene and α-C 3-12 in the presence of a metallocene catalyst.
The agricultural polyolefin-based resin laminated film according to claim 1, which is a linear low-density polyethylene obtained by copolymerization with an olefin.