JP2003210049A - Covering material for green house - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a covering material for green house inhibiting invasion of useless noxious insects, excellent in heat insulation in cold day, effect of protection or the like from wind and rain, and sufficiently retaining air permeability, having high utilization efficiency of light and low in transmission of the light. <P>SOLUTION: The covering material is a film comprising a polyolefin based thermoplastic resin which is porous having micropores, having a total light transmittance of ≤30%. The polyolefin based thermoplastic resin preferably contains ≥1 wt.% of polyolefin having a molecular chain length of ≥2850 nm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a covering material for an agricultural house for growing and cultivating crops, horticultural plants and the like. The agricultural house covering material of the present invention is particularly suitable as a covering material for a house for illuminating cultivation.

[0002]

2. Description of the Related Art In the cultivation of leafy vegetables using an agricultural house or other facility having a structure in which a sheet is attached to a frame formed of a pipe or the like, in general, it is necessary to prevent unwanted infestation of harmful insects. In addition to effects such as heat retention in cold weather and protection from wind and rain, it is required to ensure sufficient air permeability.

A sheet made of soft polyvinyl chloride is well known as an agricultural house covering material, and from the viewpoint of protection from wind and rain, the use of such a sheet provides a sufficient effect. However, the soft polyvinyl chloride sheet is a material that does not have air permeability at all, and in order to ensure air permeability of the house, the sheet is used in a structure in which the upper part of the facility is covered and the side part is opened. In this case, of the above requirements for agricultural houses, direct exposure to rainwater is prevented,
Requests for prevention of pest invasion and heat retention in cold weather cannot be achieved.

As a means for solving such a problem, Japanese Unexamined Patent Publication No. Hei 6
No. 121625 discloses a breathable horticultural covering material comprising a transparent mesh sheet and a transparent resin. According to this breathable horticultural covering material, it is possible to achieve a certain degree of demand for prevention of invasion of harmful insects and heat retention during cold weather.

[0005]

However, there are cases where electro-illumination cultivation is carried out using an agricultural house. In such electro-illumination cultivation, the utilization efficiency of the light emitted from the light source is high, It is also required that the above-mentioned light does not disturb neighboring houses, but the breathable horticultural covering material described in JP-A-6-121625 has a large light transmittance, and the light emitted from the light source is the covering material. Since the light is transmitted through, the light utilization efficiency is not improved, and the light transmitted through the covering material may be annoying to neighboring houses.

The object of the present invention is to prevent unwanted infestation of harmful insects,
Another object of the present invention is to provide an agricultural house covering material which has sufficient air permeability, high light utilization efficiency, and small light transmission, in addition to the effect of keeping heat in the cold and protection from wind and rain.

[0007]

The agricultural house coating material of the present invention comprises a film formed of a thermoplastic polyolefin resin, is porous having fine pores, and has a total light transmittance of 30% or less. Is characterized in that.

The agricultural house covering material having such a structure has water resistance capable of preventing rainwater invasion, and also has effects of preventing invasion of unnecessary pests, keeping heat in cold weather, etc. As a result, the utilization efficiency of light is high and the transmission of light to the outside is small. The light here is mainly visible light and ultraviolet rays necessary for growing agricultural products. The lower the total light transmittance and the higher the light reflectance, the better.

The polyolefin-based thermoplastic resin is 1% by weight of polyolefin having a molecular chain length of 2850 nm or more.
It is preferable to include the above.

Polyolefin resin has a molecular chain length of 285
A porous film containing a long-chain polyolefin having a long molecular chain length of 0 nm or more has excellent strength, and thus serves as a coating material having excellent mechanical strength. Further, since the film thickness can be reduced while maintaining the mechanical strength, the air permeability and the moisture permeability can be further improved, and the agricultural house coating material exhibiting the effect of the present invention can be obtained.

From the viewpoint of the strength of the agricultural house coating material, the polyolefin resin preferably contains 1% by weight or more of a long molecular chain length polyolefin having a molecular chain length of 2850 nm or more, and 10% by weight or more. It is more preferable that the content is 20% by weight or more.

The molecular chain length, weight average molecular chain length, molecular weight and weight average molecular weight of the polyolefin are measured by GPC (gel permeation chromatography), and the mixing ratio (% by weight) of the polyolefin in a specific molecular chain length range or in a specific molecular weight range is measured. ) Can be obtained by integration of the molecular weight distribution curve obtained by GPC measurement.

Here, the molecular chain length of polyolefin is a molecular chain length in terms of polystyrene by GPC (gel permeation chromatography) measurement, which will be described later, and more specifically, a parameter obtained by the following procedure.

That is, as the mobile phase for GPC measurement,
A solvent that can dissolve both the unknown sample to be measured and standard polystyrene of known molecular weight is used. First, GPC measurement is performed on a plurality of types of standard polystyrenes having different molecular weights, and the retention time of each standard polystyrene is determined. The molecular chain length of each standard polystyrene is obtained using the Q factor of polystyrene, and the molecular chain length of each standard polystyrene and the corresponding retention time are known from this. The molecular weight, molecular chain length and Q factor of standard polystyrene have the following relationships.

Molecular weight = molecular chain length × Q factor Next, GPC measurement of an unknown sample is carried out to obtain a retention time-elution component amount curve. When the molecular chain length of the standard polystyrene, which had a retention time T in the GPC measurement of standard polystyrene, is L, the “polystyrene-equivalent molecular chain length” of the component having the retention time T in the GPC measurement of the unknown sample is L
And Using this relationship, the polystyrene-equivalent molecular chain length distribution (relationship between polystyrene-equivalent molecular chain length and elution component amount) of the unknown sample is obtained from the retention time-elution component amount curve of the unknown sample.

In addition, the agricultural house coating material of the present invention has a Gurley value (air permeability) per thickness of 25 μm of 10 to 100.
It is preferably 0 seconds / 100 ml.

Gurley air permeability of 1000 seconds / 100 ml
When it exceeds, that is, the time required for aeration of 100 ml is 10
If it exceeds 00 seconds, the air permeability or moisture permeability may be too low, and the crop may become damp, and if it is less than 10 seconds / 100 ml, that is, if the time required to ventilate 100 ml is less than 10 seconds, rainwater is likely to enter.

In the agricultural house covering material of the present invention,
The fine pores preferably have an average pore diameter d of 0.06 to 3 μm. Average fine pore diameter d (μm)
Can be determined by the bubble point method (ASTM F316-86).

If the average pore diameter is less than 0.06 μm, air permeability and moisture permeability may not be sufficient, and if it exceeds 3 μm, rainwater is likely to enter.

In the agricultural house coating material of the present invention, it is preferable that the porosity is 40 to 80% because uniform and high air permeability can be obtained.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin resin constituting the agricultural house coating material of the present invention is mainly composed of a polymer of one kind of olefin or a copolymer of two or more kinds of olefins. Examples of the olefin as a raw material for the polyolefin resin include ethylene, propylene, butene, and hexene. Specific examples of the polyolefin resin include low density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), high density polyethylene and other polyethylene resins, polypropylene,
Polypropylene resin such as ethylene-propylene copolymer, poly (4-methylpentene-1), poly (butene-
1), ethylene-vinyl acetate copolymer, and the like.

In addition to the above polyolefin resin, other thermoplastic resin may be used in combination. Examples of the thermoplastic resin include styrene-based resins such as butadiene-styrene copolymer, polystyrene, styrene-butadiene-styrene copolymer, and styrene-isoprene-styrene copolymer, vinyl chloride resin, polyvinyl fluoride, polyvinyl fluoride. Vinyl fluoride resin such as vinylidene, 6-nylon,
Polyamide resin such as 6,6-nylon and 12-nylon, saturated polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyphenylene oxide, polyacetal, polyphenylene sulfide, silicone resin, thermoplastic polyurethane resin, polyether ether ketone , Polyetherimide, thermoplastic elastomers and cross-linked products thereof.

The agricultural greenhouse coating material of the present invention may contain a filler such as an inorganic filler or an organic filler.

Further, the agricultural house coating material of the present invention is a stretching aid such as a fatty acid ester or a low molecular weight polyolefin resin, a stabilizer, an antioxidant, an ultraviolet absorber, a flame retardant, etc. within a range not hindering the object of the present invention. You may contain additives, such as coloring agents, such as a pigment. In addition, it is preferable that the colorant and its addition amount do not reduce the light utilization efficiency. The agricultural house coating material of the present invention does not have a reduced total light transmittance due to the addition of carbon black or the like.

The agricultural house coating material of the present invention which is made of a polyolefin resin containing a long molecular chain length polyolefin having a molecular chain length of 2850 nm or more is, for example, a resin raw material and an inorganic compound and / or resin fine powder. Can be produced by kneading using a biaxial kneader having a segment design so that strong kneading is possible, forming a film by a roll rolling method, and stretching the obtained raw film with a stretching machine.

The polyolefin resin film thus obtained has fine pores formed by a three-dimensional network structure composed of trunk fibrils extending in one direction of the film and branch fibrils connecting the trunk fibrils. Then
The formation density of the branch fibrils is higher than that of the trunk fibrils. The pore structure of such a porous film is
It is called the oofah structure.

The porous film having such a constitution has excellent water resistance, uniform breathability and moisture permeability, and has sufficient strength. Further, the presence of the micropores having such a configuration makes the whole opaque, and the light emitted from the light source is diffusely reflected in the house due to the fine irregularities on the surface, so that the agricultural house coating material has a low total light transmittance of 30% or less. Becomes More specifically, for example, light can be reflected by setting the average pore diameter of the micropores to be equal to or larger than the wavelength of light, but preferably the average pore diameter is set to 0.06 μm or more to transmit Can be further suppressed and the light reflectance can be enhanced, and it can be an agricultural house covering material having excellent breathability and moisture permeability. Furthermore, the porosity is 40
When it is set to -80%, light is diffusely reflected due to the difference in refractive index between air and resin, and it can be an agricultural house covering material having a total light transmittance of 30% or less. Further, the agricultural house covering material having the above structure has sufficient strength.

Further, since the formation density of the branch fibrils is higher than the formation density of the trunk fibrils, it becomes an agricultural house covering material having an excellent balance of mechanical strength between the maximum heat shrinkage direction and the direction orthogonal thereto. The branch fibrils and the trunk fibrils do not necessarily have to extend linearly.
Also, the direction in which the stem fibrils extend can be confirmed by electron micrographs and is determined by cutting the film,
It is not particularly specified. "Stretching in one direction" does not require that all stem fibrils extend linearly in parallel in a specific direction, but meandering and having a certain degree of variation and being oriented in a specific direction on average. It means that

The formation densities of the branch fibrils and the trunk fibrils are the numbers of fibrils existing in the area of the film of 1 μm ² , and are determined by observing the film surface with a scanning electron microscope. Specifically, the number of fibrils existing in 5 × 5 μm is measured and obtained.

As a device used for stretching, a known stretching device can be used without limitation, and a clip tenter is exemplified as a suitable means.

As the fine powder of the above-mentioned inorganic compound, aluminum oxide or aluminum hydroxide having an average particle diameter of 0.1 to 1 μm, magnesium oxide or magnesium hydroxide,
Hydrotalcite, zinc oxide, iron oxide, titanium oxide,
Examples include calcium carbonate and magnesium carbonate.
In particular, it is preferable to use calcium carbonate and magnesium carbonate to dissolve and remove them with acidic water after producing an agricultural house coating material, in order to obtain stable air permeability and moisture permeability.

The thermoplastic resin constituting the agricultural house coating material of the present invention may be crosslinked by irradiation with radiation. The agricultural house covering material in which the thermoplastic resin is crosslinked is superior in heat resistance and strength to the agricultural house covering material made of the non-crosslinked thermoplastic resin.

The agricultural house coating material of the present invention has a thickness of 10 to 10.
It is effective to have a thin film of about 150 μm. Further, in this case, it is also effective that the thermoplastic resin constituting the agricultural house covering material is crosslinked by irradiation with radiation. Usually, when the agricultural house coating material is made thin, there is a problem that the film strength is reduced. On the other hand, the agricultural house coating material according to the present invention, the film thickness of which is about 10 to 150 μm, and the thermoplastic resin constituting the film is crosslinked by irradiation with radiation, It can be a house coating material for agriculture, which has particularly stable breathability and moisture permeability and high strength.

The film of the agricultural house coating material of the present invention in which the thermoplastic resin is crosslinked is further irradiated with radiation to the agricultural house coating material of the present invention produced using the non-crosslinked thermoplastic resin. It can be obtained by irradiation.

The type of radiation to be applied to the agricultural house coating material of the present invention for crosslinking is not particularly limited, but gamma rays, alpha rays, electron rays and the like are preferably used.
Use of an electron beam is particularly preferable from the viewpoint of production speed and safety.

As a radiation source, an accelerating voltage of 100 to 3 is used.
An electron beam accelerator of 000 kV is preferably used. If the accelerating voltage is lower than 100 kV, the electron beam penetration depth is insufficient, and if it is higher than 3000 kV, the device is large and the cost is not preferable. Examples of the radiation irradiation device include an electron beam scanning type device such as a Van de Graaff type and an electron beam fixed / conveyor moving type device such as an electron curtain type.

The absorbed dose of radiation is 0.1 to 100 Mra.
d is preferable, and 0.5 to 50 Mrad is more preferable. If the absorbed dose is less than 0.1 Mrad, the effect of cross-linking the resin is not sufficient.
When it is larger than 0 Mrad, the strength is remarkably reduced, which is not preferable.

The irradiation atmosphere when irradiating the agricultural house coating material of the present invention with radiation may be air, but an inert gas atmosphere such as nitrogen is preferred.

Further, in the agricultural house covering material of the present invention,
Other organic or inorganic compounds can be impregnated into the pores of the porous film with or without irradiation of radiation. The compound to be impregnated can be appropriately selected depending on the use of the porous film, and examples thereof include chemicals such as insecticides and agricultural chemicals.

The covering material for an agricultural house of the present invention may be used for covering the whole house, but from the viewpoint of effective utilization of sunlight, the conventional transparent film or sheet is used for the roof constituent part and the side part is used. It is also preferable to use the agricultural greenhouse coating material of the present invention as a constituent material. According to this configuration,
Although the transmittance of light to the upper side is high, annoyance to neighboring houses is prevented.

[0041]

EXAMPLES Examples will be shown below to more specifically describe the present invention, but the present invention is not limited to these examples. The physical properties of the agricultural house coating materials shown in Examples and Comparative Examples were measured by the following evaluation methods.

[Evaluation Method] (1) Gurley Air Permeability (Evaluation of Air Permeability) The Gurley air permeability (second / 100 ml) of the film is JI
According to SP 8117, it was measured with a B type densometer (manufactured by Toyo Seiki).

(2) Total light transmittance Measured by using a 330 type self-recording spectrophotometer (manufactured by Hitachi Ltd.) according to the single beam method of JIS K 7361-1. It can be said that the smaller the numerical value of the total light transmittance is, the better the performance of blocking and reflecting the light.

(3) Average pore diameter Perm-Porometer (manufactured by PMI) by the bubble point method according to ASTM F316-86.
The average pore diameter d (μm) was measured with.

(4) Puncture strength A metal needle having a diameter of 1 mm and a tip radius of curvature of 0.5 mm is attached to a film fixed with a washer having a diameter of 12 mm.
When piercing at a speed of 00 mm / min, the maximum load at which a hole was opened was measured and defined as the piercing strength.

[Manufacture of Agricultural House Coating Material] (5) Moisture Permeability According to the cup method stipulated in JIS Z 0208,
Condition for 1 hour in an atmosphere of 40 ° C. and 90% relative humidity, measure the amount of water vapor permeation 1 hour after the completion of the condition adjustment, and convert to the amount of water vapor per unit area of the film per day. And expressed as water vapor transmission rate (g / m ² · day).

(6) Hydrostatic pressure Measured according to the hydrostatic pressure A method (low water pressure method) specified in JIS L 1092, and expressed in mm water column unit.

(Example 1) Calcium carbonate (Star Piggot 15A, manufactured by Shiraishi Calcium Co., average particle size 0.15)
Polyethylene powder (Hi-Zex Million 340M, manufactured by Mitsui Chemicals, weight average molecular chain length 1)
7,000 nm, weight average molecular weight 3,000,000, melting point 136
70% by weight of polyethylene wax (Hiwax 110P, Mitsui Chemicals, weight average molecular weight 1000, melting point 110 ° C.) 30% by weight mixed polyethylene resin 70vo
Kneading was performed using a twin-screw kneader (manufactured by Plastic Engineering Laboratory Co., Ltd.) with a segment design so that 1% and 1% could be kneaded strongly. Molecular chain length 2850 in this resin composition
The polyethylene content of nm or more was 27% by weight. This resin composition is rolled (roll temperature 150
C.) to produce a raw film having a thickness of about 70 μm.

The obtained raw film was stretched about 5 times at a stretching temperature of 110 ° C. by a tenter stretching machine to obtain an agricultural house coating material composed of a porous film having a loofah structure. The scanning electron micrograph of the surface of the obtained agricultural house covering material is shown in FIG. This house coating film is
It has an oofah structure. That is, the slightly thicker fibers that meander in the V direction in FIG. 1 are the trunk fibrils, and the branch fibrils are formed in the direction orthogonal to the V direction. As is clear from FIG. 1, the formation density of branch fibrils is higher than that of stem fibrils. Many fine holes are formed by the trunk fibrils and the branch fibrils. The branch fibrils were oriented in the direction of maximum heat shrinkage.

The water pressure resistance, air permeability, moisture permeability, total light transmittance, film thickness of the agricultural house coating material obtained in Example 1
Table 1 shows the measurement results of the average pore diameter d and the puncture strength.

Example 2 A commercially available porous film was used as an agricultural house coating material. This porous film is produced by forming a resin composition consisting of 40% by weight of polyethylene and 60% by weight of calcium carbonate (average particle size 1.25 μm) by a T-die molding machine and stretching by a roll stretching machine. And does not have a loofah structure. The physical properties of this porous film are also shown in Table 1. When GPC measurement was performed on the polyethylene constituting this film, the content of polyethylene having a molecular chain length of 2850 nm or more was less than 1%. Table 1 shows the measurement results of water pressure resistance, air permeability, moisture permeability, film thickness, average pore diameter d, puncture strength, and total light transmittance of this agricultural house covering material.

Comparative Example 1 Another commercially available porous film was used as an agricultural house coating material. This porous film has a high draft ratio (take-off speed / extrusion speed ratio)
Porosity manufactured by subjecting polypropylene / polyethylene / polypropylene laminated film molded in to a crystallized heat treatment to form a highly ordered crystal structure, and then stretching at low temperature and then at high temperature to peel off the crystal interface. It is a film. This commercially available porous film has a structure in which the gaps of the laminated lamella crystals are pores. Table 1 shows the measurement results of water pressure resistance, air permeability, moisture permeability, film thickness, average pore diameter d, puncture strength, and total light transmittance of this agricultural house covering material.

[0053]

[Table 1] The porous films of Examples 1 and 2 were washed with an aqueous acid solution,
After drying, a load test was conducted. In the load test, the porous film was a 5 cm x 5 cm aluminum plate (thickness 0.5 m
m) and a load of 70 kg from above (2.8 kg
/ Equivalent to cm ² ) for 30 seconds. The load of 70 kg assumes the weight of an adult male. Table 2 shows the measurement results of the Gurley value before and after the load test.

[0054]

[Table 2] From the results shown in Table 2, after the load test, the air permeability of the porous film of Example 1 was almost maintained, but the air permeability of the porous film of Example 2 was about 1.4 times. .

[0055]

Industrial Applicability The agricultural house coating material of the present invention is a film formed of a thermoplastic polyolefin resin, which has fine pores and a total light transmittance of 30% or less. Therefore, when used in an agricultural house, it can effectively prevent rainwater and pests from entering the house and ensure sufficient ventilation, and further increase the light utilization efficiency, It is also possible to suppress the transmission of light to the outside of the house. In addition, the above-mentioned polyolefin-based thermoplastic resin can provide an agricultural house coating material having excellent mechanical strength by containing 1% by weight or more of a polyolefin having a molecular chain length of 2850 nm or more, and is good. Since the film thickness can be reduced while maintaining good mechanical strength, air permeability and moisture permeability can be further improved.

[Brief description of drawings]

FIG. 1 is an electron micrograph of an agricultural house covering material of Example 1.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Hanada             Sumitomo, 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture             Gaku Kogyo Co., Ltd. (72) Inventor Takeshi Yamada             2-10-1, Tsukahara, Takatsuki City, Osaka Prefecture             Within Lastec Co., Ltd. F-term (reference) 2B024 DB01 DD01                 2B029 EB02 EB22 EC02 EC12 EC13                 4F074 AA16 AA17 AB01 AB03 AC26                       CA01 CA06 DA03 DA24 DA46

Claims (3)

[Claims] 1. An agricultural house covering material comprising a film formed of a polyolefin-based thermoplastic resin, being porous having fine pores, and having a total light transmittance of 30% or less. 2. The thermoplastic polyolefin-based resin,
The agricultural house coating material according to claim 1, which comprises 1% by weight or more of a polyolefin having a molecular chain length of 2850 nm or more. 3. The average pore diameter d of the fine pores is 0.0
It is 6-3 micrometers, The agricultural house coating material of Claim 1 or 2.