JP2007089493A - Agricultural film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agricultural film excellent in antifogging property and moisture permeability and used for lining or covering of greenhouse culture, growing, etc., in plastic tunnel. <P>SOLUTION: The agricultural film has a plurality of fine holes obtained by boring a thermoplastic resin film with a needle having spinous processes and has ≥500 (g/m<SP>2</SP>, 24hr) moisture permeability or the film is a thermoplastic resin film having a plurality of fine holes in which the form has a spinate part and having ≥500 (g/m<SP>2</SP>, 24hr) moisture permeability. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an agricultural film used for lining or outer lining such as house cultivation and tunnel cultivation, and particularly preferably relates to an agricultural film excellent in antifogging property and moisture permeability.

  Conventionally, as a method for forcibly cultivating agricultural crops, so-called house cultivation and tunnel cultivation in which plants are cultivated under agricultural film covering such as vinyl chloride resin films and olefin resin films have been actively performed.

  In such house cultivation, tunnel cultivation, etc., the temperature, humidity, etc. in the house or tunnel have a great influence on the growth of crops, so adjustment according to the climate is necessary.

  In particular, in house cultivation, which has recently increased in size, in addition to the agricultural film for the outer stretch that is fixedly stretched on the house frame, the agricultural film for the inner liner is used as a so-called curtain material in the house or as a solid covering material that further covers crops. The method of using has been performed.

  In particular, in the agricultural film for lining, if moisture permeability (breathability) is low, water vapor in warm air may be trapped in the film, which may cause a high humidity disorder on the crop. In addition, water vapor adheres to the inner surface of the film to form water droplets, and as a result, the phenomenon that the transparency of the film decreases is one of the problems, and moisture permeability (breathability) and anti-fogging properties are required. .

  Further, as the agricultural film for the outer layer, a film having insectproof / rainproof properties and air permeability (moisture permeability) is preferable, but an agricultural film for outer layer having the air permeability has not been obtained yet. In addition, the antifogging property is an important performance in agricultural films for outer layers, and conventionally, a method of spraying an antifogging agent on the inner surface during house extension, a method of kneading a surfactant on the inner surface of the film, In addition, a method of applying a coating layer containing special inorganic fine particles to the inner surface of the film is taken, but it takes time and cost, and sufficient antifogging properties cannot be obtained.

  Conventionally, in agricultural films for lining, nonwoven fabric has been used as an agricultural material having air permeability. However, the nonwoven fabric is excellent in breathability, but it is a white opaque material and has the disadvantage of low light transmittance, and it cannot be used for crops that require sufficient sunlight irradiation for growth. There was a problem.

On the other hand, some agricultural films have been proposed in which a non-porous film made of a synthetic resin film is provided with air holes and water holes. For example, Patent Document 1 discloses an agricultural film in which vent holes having a diameter of 1.5 mm or less are provided so that the total area of the vent holes is 10 to 60% of the film surface area. Moreover, in patent document 2, in order to eliminate the so-called fishbowl phenomenon in which water droplets condensed on the inner surface of the outer covering material fall on the inner curtain to form a puddle, a diameter is formed on the synthetic resin film as a drain hole. A perforated film for agriculture for lining curtains having at least one through hole of 1 mm or more and 4 mm or less per 1 m ² is disclosed. As one of the hole making methods, a needle punching method for making a hole with a needle has been proposed.

However, in the conventional perforated film, it is necessary to reduce the size of the hole in order to achieve waterproofing and heat retention, but on the other hand, there is a drawback that sufficient ventilation is not performed, and in order to ensure air permeability However, when the size of the air vent is increased, there is a contradictory problem that the waterproof and insect-proofing effect and the heat retaining effect are reduced.
Japanese Utility Model Publication No. 5-74249 No. 5-10598

  Thus, an object of the present invention is to provide an agricultural film having moisture permeability (breathability), anti-fogging property, and drip-proof adhesion, and having heat retaining properties and waterproof insect-proofing effects without lowering transparency. There is.

  The inventors of the present invention have found that the use of a perforated resin film having a plurality of micropores that have been perforated with a specially-shaped needle as the thermoplastic resin film solves the above-mentioned problems. A patent application was filed as application 2005-103837 (priority date March 31, 2004). Then, as a result of further investigation, in addition to solving the above-mentioned problems by controlling the moisture permeability of the porous resin film, it was found that very excellent cultivatability was obtained, and the present invention was reached.

That is, the gist of the present invention is:
(1) A thermoplastic resin film having a plurality of fine holes obtained by drilling with a needle having a spinous process, and having a moisture permeability of 500 (g / m ² .24 hr) or more. Agricultural film,
(2) An agricultural film formed of a thermoplastic resin film having a plurality of micropores, wherein the micropores have a spiny shape having barbs, and are 500 (g / m ² .24 hr) or more. Agricultural film characterized by having moisture permeability,
(3) Agriculture according to (1) or (2), characterized in that it has a plurality of fine holes obtained by drilling with a needle having a spinous process from one side or both sides of a thermoplastic resin film. For film,
(4) The agricultural film as set forth in any one of (1) to (3), wherein the film has fine protrusions on both sides thereof.
(5) The agricultural film according to any one of (1) to (4), wherein the resin constituting the thermoplastic resin film is a vinyl chloride resin or an olefin resin,
(6) The thermoplastic resin film is a resin film having a multilayer structure of three or more layers having at least an outer layer, an intermediate layer, and an inner layer, and the resin constituting the outer layer and / or the inner layer includes at least a metallocene-based polyethylene resin. (1) to (6), wherein the film for agriculture according to any one of (1) to (5) and (7) holes obtained by spot drilling are further provided. Agricultural film,
Exist.

  According to the present invention, moisture permeability (breathability), anti-fogging property, drip-proof adhesion, heat insulation and waterproof insect-repellent effect are obtained without lowering transparency, and further excellent cultivatability. The resulting agricultural film can be obtained.

  Hereinafter, the present invention will be described in detail.

  The agricultural film (moisture permeable film, antifogging film) of the present invention is a perforated resin film in which a plurality of fine holes are provided in a thermoplastic resin film.

  Examples of the resin constituting the thermoplastic resin film include vinyl chloride resin, polyethylene, ethylene-vinyl acetate copolymer, polyolefin resin such as polypropylene, polyester resin such as polyethylene terephthalate, polymethyl methacrylate resin, and fluorine resin. Any known thermoplastic resin conventionally known as a material for agricultural films, moisture-permeable films, and antifogging films can be used. Preferably, a soft vinyl chloride resin or polyolefin resin is used.

  Examples of polyolefin resins include α-olefin homopolymers, copolymers of different monomers mainly containing α-olefins, polyunsaturated compounds such as α-olefins and conjugated dienes or nonconjugated dienes, Examples include copolymers with acrylic acid, methacrylic acid, vinyl acetate, and the like, such as high density, low density or linear low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene. Examples include -4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer. Among these, low density polyethylene having a density of 0.910 to 0.935, an ethylene-α-olefin copolymer, and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by weight or less have transparency and weather resistance. It is preferable as an agricultural film from the viewpoint of properties and price.

  In the present invention, it is preferable to use a metallocene polyethylene resin, that is, an ethylene-α-olefin copolymer resin obtained by copolymerization with a metallocene catalyst, as at least one component of the resin constituting the thermoplastic resin film. This is usually referred to as metallocene polyethylene, and is a copolymer of ethylene and an α-olefin such as butene-1, hexene-1, 4-methylpentene-1, octene, and the like. can get.

As the metallocene-based polyethylene resin, it is preferable to use one having the following physical properties. MFR measured by JIS-K7210 shows a value of 0.01 to 10 g / 10 min, preferably 0.1 to 5 g / 10 min, and a density measured by JIS-K7112 is 0.880 to 0.930 g / The molecular weight distribution (weight average molecular weight / number average molecular weight) determined by gel permeation chromatography (GPC) is 1.5 to 3.cm ³ , preferably 0.880 to 0.920 g / cm ³ . 5, preferably a metallocene polyethylene resin showing a value of 1.5 to 3.0.

  In the present invention, the thermoplastic resin film as the base film may be composed of a single layer or a multilayer film composed of two or more layers.

  In a preferred embodiment of the agricultural film in the present invention, the base film made of the polyolefin resin composition is a multi-layer film composed of at least three layers of an outer layer, an intermediate layer, and an inner layer that are outside when stretched. In addition, an ethylene-α-olefin copolymer resin obtained by copolymerization with a metallocene catalyst as a resin component of the outer layer or the outer layer and the inner layer that becomes the outer side during stretching is 45% by weight to 100% by weight, preferably 55% by weight. The resin composition containing 95% by weight or less is used, and the ethylene-vinyl acetate copolymer is 45% by weight or more and 100% by weight or less, preferably 55% by weight or more and 98% by weight or less in the intermediate layer or the intermediate layer and the inner layer. It is preferable to use the resin composition contained. In the present invention, as the resin component of the outer layer, the intermediate layer, and the inner layer, an ethylene-α-olefin copolymer resin obtained by copolymerization with a metallocene catalyst is 45% by weight to 100% by weight, preferably 55% by weight. A resin composition containing from 95% to 95% by weight can also be used.

  As used herein, the outer layer means a layer that becomes an outer side when used as an agricultural film, and the inner layer means a layer that becomes an inner side when used.

  The production method of the resin film having a multilayer structure is not particularly limited, and a known production method can be used, and the layer thickness ratio of the multilayer structure is not particularly limited. The range of 1 / 0.5 / 1 to 1/5/1 is preferable, and the range of 1/2/1 to 1/4/1 is more preferable from the viewpoint of properties, transparency, and strength. Further, the ratio between the outer layer and the inner layer is not particularly specified, but it is preferable that the ratio is approximately the same because of the curl property of the obtained film.

  The thickness of the thermoplastic resin film is 10 to 1000 μm, preferably 20 to 200 μm. If it is too thin, the strength of the film after perforation tends to be insufficient. On the other hand, if it is too thick, it is difficult to make holes, which is not preferable.

  In addition, the thermoplastic resin film used in the present invention can be blended with any known additive depending on its use. For example, a plasticizer, an ultraviolet light inhibitor, a light stabilizer, a heat retaining agent, a lubricant, and various other additives can be mentioned.

  Moreover, the agricultural film of this invention can form a coating film other than that. For example, a dust-proof coating film may be formed on the outer layer of the film, or if a further anti-fogging coating film is formed on the inner layer of the film, the effect and synergistic effect of the micropores of the present invention are brought about. An effect is obtained. As the anti-fogging coating, various known coatings can be adopted as coatings for agricultural films. Preferably, for example, inorganic colloidal sols such as silica sol and / or alumina sol, and binder resins such as thermoplastic resins are used. And the like. Examples of the thermoplastic resin include hydrophobic or hydrophilic acrylic resins and urethane resins.

  Examples of the agricultural film to which the present invention is applied include a lining film or an outer lining film in house cultivation or tunnel cultivation, a solid film covering a plant as it is, other multi-films and mats for raising seedlings, etc. Or a film for an outer layer is preferred.

  The present invention is characterized in that the micropores provided in the thermoplastic resin film are special micropores. Specifically, these special micropores are obtained by a special needle drilling method that applies the needle pricker processing method, which is a machine mainly used for texture processing of nonwoven fabrics, fabrics, and artificial leather. is there.

  Specifically, as shown schematically in FIG. 1, it is obtained by piercing a thermoplastic resin film with a specially shaped needle 1 having one or more fine barbs 1c on the outer peripheral portion of the needle (needle).

  FIG. 1 is an enlarged view of the needle 1, FIG. 1a shows a front view, and FIG. 1b shows a side view. The needle 1 is pointed from the base portion 1a toward the tip portion, and a cutting edge 1b having a minute width (W) is provided at the tip portion. Since the minute width of the tip portion is related to the size of the basic portion of the hole formed in the resin film, it is preferably 10 μm to 300 μm, more preferably 30 μm to 150 μm.

  Moreover, the special needle 1 used in the present invention has one or more, preferably two or more, fine spines 1c on a part of the outer periphery of the needle near the tip. The spine protrudes in a direction substantially perpendicular to the axis of the needle, and the shape of the spine is only required to be pointed from the base to the tip. The spine 1c is, for example, 300 to 1000 μm from the tip of the needle. It is preferable that one is provided at a position of 800 to 2000 μm. The length of the barb 1c itself is preferably in the range of 1 μm to 300 μm.

  As shown in FIG. 2, the needle 1 having these barbs preferably forms a plurality of needle rolls 2 attached to a roll body 2, and is used for processing on a plane or wound around another roll body. By pressing and rotating the needle roll against the thermoplastic resin film 3, a plurality of micropores can be formed in the thermoplastic resin film. In addition, according to the number and space | interval of a required fine hole, you may employ | adopt the method of processing with the several needle roll with respect to the resin film 3, or pressing a resin film against a needle roll in multiple times. In addition, as one of the preferable embodiments of the present invention, as described later, a method of perforating a resin film from both sides is preferable for reducing the curling property of the film. In this case, the double-sided processing may be performed at the same time, but the method of performing the perforating processing for one surface is usually simpler.

  FIG. 3 shows a schematic view of the shape of individual micropores provided in the thermoplastic resin film with such a specially shaped needle. The shape of the micropores can be confirmed by an enlarging means such as a microscope. The shape of the fine hole 4 formed in the film of the present invention is not a circular hole shape formed by a normal needle due to the presence of the barbs 1c, but as shown in the schematic diagram of FIG. The shape has one or more minute spine-shaped notches 4b around. Here, the shape of the basic hole 4a can take various shapes and is not limited. Non-limiting examples include a substantially circular shape as shown in FIG. 3 and a polygon such as a substantially triangular shape and a substantially rectangular shape. In addition, the number of the spine-shaped notches is one or more, preferably two or more. In many cases, the number of the spines 1c is equal to or more than the number of the barbs 1c provided on the used needle 1.

  Although the mechanism for obtaining the excellent anti-fogging effect and moisture permeation effect of the present invention is not clear, the shape of the shape formed by connecting the basic hole portion with a large gap and the spiny notch portion with a small gap in this way. It is presumed to be obtained by a synergistic effect.

  When the basic hole 4a is substantially circular, the maximum diameter is at least 500 μm or less, preferably 200 μm or less, and the minimum diameter is 10 μm or more, preferably 20 μm or more. When the basic hole 4a is substantially square, the maximum side length is at least 500 μm or less, preferably 200 μm or less, and the minimum side length is 10 μm or more, preferably 20 μm or more. Furthermore, the length of the spine-shaped notch 4b is preferably 100 μm or less to 0.05 μm or more, more preferably 50 μm or less to 0.1 μm or more.

  In FIG. 5, the conceptual diagram of the film which provided the fine hole of this invention in multiple numbers is shown.

  Further, when the needle having a barb is stabbed into and pulled out from the resin film, the needle has a function of hooking a piece around the notch part and projecting a section 4c around the barb notch part 4b in the piercing direction. Therefore, the film having a plurality of micropores obtained by the special needle drilling method according to the present invention has a special shape when the cross section of the film is viewed.

  That is, FIG. 4 shows a schematic image of a cross-sectional view of the micropores provided in the film of the present invention. Among the resin film 3, a partial slice 4c around the microscopic spine-shaped notch 4b is shown in FIG. It has a minute protrusion shape that slightly protrudes in the direction in which the needle 1 is pierced. As shown in FIG. 4, the minute protrusions may have shapes in which the sections 4 c are open, or may be convex protrusions formed by overlapping the sections 4 c partially or entirely.

  As a result, in the film having micropores of the present invention, the surface roughness Ra1 of the film surface (P in FIG. 4) on the side pierced with the needle is compared with the film surface Ra (Q in FIG. 4) roughness Ra2 on the opposite side. Therefore, there is a relationship of Ra1 <Ra2. In this case, Ra1 is close to the surface roughness derived from the original film. Moreover, although surface roughness Ra2 changes also with film thickness, the protrusion height (Hc) of the film surface to the direction which stabbed the needle with respect to film thickness (Ha) is Hc / Ha = 0.4. The surface roughness is about ˜2, preferably about 0.5˜1.

  When using the agricultural film of the present invention, basically, either side of the film may be used inside. However, as a preferred method of use, the surface side having anti-fogging property or the humid side may be used. A favorable effect can be obtained by arranging a surface (Ra2) having a rough surface roughness.

  On the other hand, as another preferred embodiment of the agricultural film of the present invention, it is possible to use a double-sided perforated film obtained by performing needle piercing from both sides of the thermoplastic resin film. By performing perforating from both sides, curling property that the film is rounded in one direction can be reduced. Moreover, the same conditions may be sufficient as the drilling process from both surfaces, and different conditions (a hole size, a density) may be employ | adopted.

The number per unit area of the plurality of fine holes provided in the thermoplastic resin film of the present invention varies depending on the area of the provided holes, but in order to exhibit preferable antifogging properties and moisture permeability and satisfy other physical properties 1 square inch (6.45 cm ²⁾ 600-8,000 per (i.e., 1 cm ² 90-1,250 per) range, more preferably 800 to 6000 cells per square inch ⁽² 120-930 per 1 cm), Even more preferably, it is preferable to provide 800 to 4000 (120 to 620 per 1 cm ² ).

  In the present invention, it is possible to obtain excellent cultivatability by suitably controlling the total area occupied by the micropores of the shape formed by connecting the basic hole portion and the spinous cutout portion per unit area of the film. it can. Here, the total area of the micropores per unit area can also be expressed by the preferred size of the micropores and the number per unit area. For example, when the basic hole is substantially circular, when the number of micro holes having a diameter of 500 μm to 10 μm is in the range of 600 to 8000 per square inch, when the basic hole is substantially square, the maximum side length is Is 500 μm or less, and the minimum side length is 10 μm or more in the range of 600 to 8000 per square inch.

  On the other hand, as described above, in the present invention, it is possible to perform hole forming from both sides of the thermoplastic resin film, and it is also possible to perform hole forming with a plurality of rolls. Multiple drilling operations can be performed at the site. In such a case, the total area substantially occupied by the micropores per unit area of the film may not be appropriately expressed only by the size of the micropores obtained and the number of micropores per unit area. Even in such a case, the moisture permeability of the film obtained by perforating can suitably represent the total area of the fine holes per unit film area. In the present invention, moisture permeability is preferably measured by the calcium chloride method of JIS L1099-1993.

The moisture permeability of the agricultural film in the present invention is preferably 500 (g / m ² .24 hr) or more, more preferably 1000 (g / m ² .24 hr) or more. If the moisture permeability is less than 500, it is not possible to obtain a significant improvement effect in cultivatability as described later. On the other hand, when the moisture permeability is increased, the degree of air ventilation (the ventilation rate described later) increases, and as a result, good cultivatability is brought about. However, if the moisture permeability is too high, there is a concern that the strength of the perforated resin film is lowered. Therefore, it is preferably 20000 or less, more preferably 16000 or less, and even more preferably 12000 or less.

  The agricultural film of the present invention can also have relatively large holes (usually holes in mm) obtained by spotting using a conventional needle punching method or the like. In this case, the film after providing the hole of a mm unit has the moisture permeability of the said range.

  The agricultural film of the present invention preferably further has transparency. Specifically, the total light transmittance at 555 nm of a film having a plurality of fine holes is preferably 70% or more, and more preferably 75% or more. This value can be measured by a known measurement method.

  In the present invention, the needle precker method is applied to a light-shielding agricultural film having a layer containing a near-infrared absorber for the purpose of light shielding in summer (for example, see JP-A No. 2000-14255). A perforated resin film can also be obtained.

  Hereinafter, although it demonstrates in detail based on this invention, this invention is not limited to the following examples, unless the summary is exceeded.

(1) Preparation of substrate film As a thermoplastic resin film for testing, a laminated film (0.05 mm thick) using the following polyolefin resin (three-layer structure formed by a three-layer inflation die) was used as a substrate film. used.

  Base film: as outer layer resin and inner layer resin, polyethylene resin (MePE) produced by metallocene catalyst as main component (90% by weight), intermediate layer resin as vinyl acetate resin with 15% by weight vinyl acetate As a base film, a film containing appropriate amounts of a heat retaining agent (hydrotalcite), an ultraviolet absorber, and a light stabilizer was used as various additives.

(2) Needle processing method By the perforation method using the needle precker needle of the shape shown in FIG. 1 attached to a plurality of rolls as shown in FIG. Examples 1), 1000 (Example 2), and 2000 (Example 3) holes were prepared on both sides so that holes could be formed.

  In addition, as a comparative example, 100 holes (comparative example 2) and 400 (comparative example 3) holes per square inch were formed in the above-described base film without perforation by a needle precker. In order to be able to do so, a film (Comparative Example 4) in which holes having a diameter of 2 mm were spot-punctured at intervals of 10 cm × 10 cm using a normal hot-melt needle on the base film and the above-mentioned base film. Prepared.

(3) Evaluation method About each obtained film, the following evaluation tests were done.
1. Transparency test The direct light transmittance and total light transmittance at 555 mm of the films obtained in Examples or Comparative Examples were measured with a spectrophotometer (Hitachi U-2000 model), and the values were shown.
2. Moisture permeability The moisture permeability of the films obtained in Examples and Comparative Examples was measured by the calcium chloride method described in JIS L1099-1993.
3. Measurement of ventilation rate Next, the ventilation rate was measured by the following method as a measure of the air permeability of the film.
A film was stretched on the upper surface of a glass container (length 400 mm × width 200 mm × height 300 mm), and the ventilation frequency (times h ⁻¹ ) was determined by measuring the change over time of the CO ₂ concentration in the container. The ventilation rate (m ³ m ⁻² h ⁻¹ ) was determined by dividing the ventilation frequency by the film area. During the measurement, there was no wind inside and outside the container.
_{N = - (lnC 1 -lnC 2} ) / (t 1 -t 2)
N: Number of ventilations (times h- ¹ )
C ₁ : CO ₂ concentration difference (molmol ⁻¹ ) inside and outside the chamber at time t ₁
C ₂ : CO ₂ concentration difference inside and outside the chamber at time t ₂ (mol mol ⁻¹ )
Ventilation rate (m ³ m ⁻² h ⁻¹ ) = Ventilation frequency (times h ⁻¹ ) / film surface area (m ² )
4). Plant Cultivation Test A 1 m × 2 m tunnel constructed at a test site of MKV Platec Co., Ltd. was coated with the films obtained in Examples and Comparative Examples, and a cultivation test was conducted. The test was started in December 2004, harvested in March 2005, and the living weight at the time of harvest was measured. The cultivated plants are mizuna, chingensai, salmon, spinach and spring chrysanthemum. The degree of growth of the cultivated plants and the total weight of the harvested plants were evaluated as cultivation test results.

実施例１〜３及び比較例１〜４で得られたフィルムを用いて、上記１〜４の評価試験を行った結果を表１に示す。表１が示すとおり、本発明の農業用フィルムは、透明性が高く、通気性の尺度としての換気率が従来のスポット穿孔フィルムより高い値を示し、更に栽培性は顕著に優れている。

Table 1 shows the results of the evaluation tests 1 to 4 described above using the films obtained in Examples 1 to 3 and Comparative Examples 1 to 4. As Table 1 shows, the agricultural film of the present invention has high transparency, a ventilation rate as a measure of air permeability is higher than that of a conventional spot perforated film, and the cultivatability is remarkably excellent.

(5) Measurement of thermal conductivity of film As shown in the above evaluation results, the agricultural film of the present invention has high air permeability, and also compared with a normal non-porous film (Comparative Example 1). Cultivation is very good. This means that the agricultural film of the present invention has a high frequency of air coming and going through the micropores and can increase the metabolism of crops, and at the same time has a heat retention equivalent to that of a conventional nonporous film. Is predicted. In order to clarify this point, as a measure of the heat retaining property of the film, the thermal conductivity due to the conduction of the film was measured using a simple measuring device shown in FIG. Two insulated containers that were ventilated were connected. The transfer of heat between the two containers takes place only via a film stretched between the containers. A lamp with a known calorific value was installed in one container. The temperature at the inlet and outlet of the insulated container was measured, and the heat transmissivity was calculated from the temperature when it became steady.
Heat transmission coefficient ^{(Jm -2 s -1 ℃ -1)} = { flow rate ^{(m 3 s -1)} × temperature difference between the inflow outlet (° C.) × heat capacity ^{(Jm -3} ℃ ^-1) ÷ temperature difference between both the container (° C)} ÷ film area (m ² )

  Using the films obtained in Example 3 and Comparative Example 1, the heat reflux rate was measured by the above method.

Moreover, the heat transmissivity by ventilation of a film can be obtained with the following formula | equation using the ventilation rate calculated | required above.
Heat transmission coefficient due to ventilation ^{(Jm -2 s -1 ℃ -1)} = ventilation rate ^{(m 3 m -2 s -1)} × air capacity ^{(Jm -3} ℃ ^-1)
Table 2 shows the results obtained by the above test method.

表２から分かるとおり、本発明の微細孔を有する農業用フィルムは、驚くべきことに、無孔フィルムとほとんど同じレベルの伝導による熱貫流率を有しており、更に、換気による熱貫流率は伝導による熱貫流率に比べて無視し得るほど値が小さい。このことから、本発明の農業用フィルムは、特定の微細孔を設けることにより微細孔を通して空気の換気レベルを高めるとともに、微細孔からの熱の散逸が非常に小さいために無孔フィルムと同等の保温性を有することが確認された。

As can be seen from Table 2, the agricultural film with micropores of the present invention surprisingly has a heat transmissivity with almost the same level of conduction as the non-porous film, and the heat transmissivity due to ventilation is The value is negligibly small compared to the heat conductivity due to conduction. From this, the agricultural film of the present invention increases the air ventilation level through the micropores by providing the specific micropores, and the heat dissipation from the micropores is very small, so it is equivalent to the nonporous film. It was confirmed to have heat retention.

The figure which shows the front view of the needle which has a spinous process for forming the micropore of this invention The figure which shows the side view of the needle which has a spinous process for forming the micropore of this invention Conceptual diagram of film processing with a needle for forming micropores of the present invention The conceptual diagram which shows the hole shape of the micropore formed in the thermoplastic resin film of this invention The conceptual diagram which shows the cross section of the hole shape of the micropore formed in the thermoplastic resin film of this invention The conceptual diagram which shows the thermoplastic resin film which has multiple spiny-shaped micropores which have a spine part of this invention Schematic diagram of thermal conductivity measurement device

Claims (7)

Agricultural film characterized by having a plurality of fine holes obtained by drilling with a needle having spinous processes in a thermoplastic resin film and having a water vapor transmission rate of 500 (g / m ² .24 hr) or more. . An agricultural film formed of a thermoplastic resin film having a plurality of micropores, wherein the micropores have a spiny shape having barbs, and have a moisture permeability of 500 (g / m ² .24 hr) or more. Agricultural film characterized by having.   The agricultural film according to claim 1 or 2, comprising a plurality of micropores obtained by drilling with a needle having a spinous process from one side or both sides of the thermoplastic resin film.   The agricultural film according to any one of claims 1 to 3, wherein the film has fine protrusions on both sides.   The agricultural film according to any one of claims 1 to 4, wherein the resin constituting the thermoplastic resin film is a vinyl chloride resin or an olefin resin.   The thermoplastic resin film is a resin film having a multilayer structure of three or more layers having at least an outer layer, an intermediate layer, and an inner layer, and the resin constituting the outer layer and / or the inner layer contains at least a metallocene-based polyethylene resin. The agricultural film according to any one of claims 1 to 5.   The agricultural film according to claim 1, further comprising holes obtained by spot perforation.

Images