Agricultural film, agricultural covering material, and agricultural covering body

Abstract

The present invention provides an agricultural film, an agricultural covering material, and an agricultural covering body that have high moisture permeability and light permeability and are excellent in handling properties such as for rolling-up and folding when being used for agricultural purposes.　An agricultural film 12 contains a cellulose acylate and a polyester. The cellulose acylate includes at least one type of acyl substituent having an acyl substitution degree of two or greater and a carbon number of three or greater. The polyester is represented by a specific formula with a weight average molecular weight of 50,000-1,000,000. At least one film surface of the agricultural film 12 has a contact angle of 50° or less.

Description

Agricultural film, agricultural covering material, and agricultural covering body

[0001] The present invention relates to an agricultural film, an agricultural covering material, and an agricultural covering body.

[0002] Cellulose acetate film has high transparency and moisture permeability, and thus is used in a wide range of applications such as agricultural materials for agricultural greenhouses. For example, as shown in Patent Document 1, in an agricultural greenhouse, in order to enhance the humidity retention inside the greenhouse, while allowing ventilation between the outer greenhouse and the inner greenhouse, a cellulose acetate film with high transparency and moisture permeability is used for the inner greenhouse that covers the plants. On the other hand, in agricultural applications, as in Patent Document 2, in order to improve the growth of seedlings inside an agricultural greenhouse and the harvest of fruits and vegetables, air enriched with carbon dioxide is also supplied.

[0003] International Publication No. 2016 / 103898, Japanese Unexamined Patent Application Publication No. 2023 - 175633

[0004] When supplying air enriched with carbon dioxide to the inside of an agricultural covering body that covers plants with an agricultural covering material for the above-mentioned inner greenhouse, if the volume of the agricultural covering body is large, there is a problem in appropriately controlling the carbon dioxide enrichment environment around the plants. For this reason, if one tries to reduce the volume of the agricultural covering body to make it compact according to the growth environment of the plants, excessive humidity may occur due to water release from the plants, and the light transmittance may decrease due to dew condensation inside the agricultural covering body. Also, when the agricultural covering body is made compact, during operations such as growing management and harvesting of the plants, it is necessary to roll up or bend the agricultural covering material to increase the volume of the agricultural covering body according to the operation, and there is a problem in the handling property of the agricultural covering material.

[0005] An object of the present invention is to provide an agricultural film, an agricultural covering material, and an agricultural covering body that have high moisture permeability and light transmittance and are also excellent in handling properties such as rolling up and bending even when used for agriculture.

[0006] The agricultural film of the present invention comprises a cellulose acylate having an acyl group substitution degree of 2 or more and at least one acyl substituent with 3 or more carbon atoms, and a polyester of general formula (1) or general formula (2) having a weight-average molecular weight of 50,000 to 1,000,000, and the contact angle of at least one of the film surfaces is 50 degrees or less. In formula (1), R1 and R2 are each alkyl groups, which may be the same or different, and n is an integer of 1 or more. In formula (2), R3 is an alkyl group, and n is an integer of 1 or more.

[0007] It is preferable that the equilibrium moisture content at 25°C and 80% RH is 2% or less. It is also preferable that the resistance strength is 500 cycles or more.

[0008] It is preferable to have a first layer containing cellulose acylate and polyester, and a hydrophilic layer with a contact angle of 50 degrees or less. It is preferable to have a hydrophilizing agent to make the contact angle 50 degrees or less. The hydrophilizing agent is preferably a long-chain alkyl sulfonic acid. The contact angle becomes 50 degrees or less 1 minute after dropping pure water, and it is preferable that the hydrophilizing agent is a silicone drip agent having a structure in which polyether groups are introduced to the ends or side chains of the silicone chain.

[0009] It is preferable to have a first layer containing cellulose acylate, polyester, and a hydrophilic agent. It is preferable to have a first layer containing cellulose acylate and a hydrophilic agent, and a second layer containing cellulose acylate and polyester. It is preferable to have a first layer containing cellulose acylate, polyester, and a hydrophilic agent, and a second layer containing cellulose acylate and polyester. The agricultural covering material of the present invention uses the agricultural film of the present invention.

[0010] The agricultural covering of the present invention is an agricultural covering that includes the agricultural film of the present invention described above, which is provided at least on the upper part and covers a plant body standing upright from the plant bed, and has a ventilation pipe that supplies carbon dioxide-enriched air to the inside of the agricultural covering.

[0011] The agricultural film is preferably placed on the side of the agricultural covering. It is preferable that it has ventilation openings on the inside of the agricultural covering that can adjust temperature and humidity. It is preferable that it has an agricultural film with a height-adjustable film section that can change height, and an agricultural film with a fixed height film section that has a fixed height, and that the plant is covered by the height-adjustable film section and the height-fixed film section.

[0012] The agricultural film has a height-adjustable film section, and it is preferable that the plant body is covered by the height-adjustable film section. It is preferable that it be placed inside an agricultural greenhouse.

[0013] According to the present invention, the material has high moisture permeability and light transmission, and is also easy to handle, such as when rolled up or folded, even when used for agricultural purposes.

[0014] This is a schematic diagram of an agricultural film consisting of a first layer and a hydrophilic layer. This is a schematic diagram of an agricultural film consisting of a first layer. This is a schematic diagram of an agricultural film consisting of a first and second layer with a different material composition than that of Figure 4. This is a schematic diagram of an agricultural film consisting of a first and second layer with a different material composition than that of Figure 3. This is a schematic front view of an agricultural covering. This is a schematic side view of an agricultural covering. This is a schematic diagram of an agricultural covering having a height-adjustable film section and a height-fixed film section. This is a schematic diagram of an agricultural covering having a height-adjustable film section. This is a schematic diagram of an agricultural greenhouse and an agricultural covering. This is a schematic diagram of an apparatus for producing sheets by melt film formation. (A) is a graph showing the change in contact angle over time after dropping pure water when no silicone drip agent is added, and (B) is a graph showing the change in contact angle over time after dropping pure water when silicone drip agent is added.

[0015] The agricultural film of the present invention is used for agricultural purposes and comprises cellulose acylate and polyester. The cellulose acylate and polyester described below are used in agricultural films 12, 14, 18, and 20 shown in Figures 1 to 4.

[0016] The cellulose acylate contained in the agricultural film of the present invention preferably has an acyl group substitution degree of 2 or more and at least one acyl substituent with 3 or more carbon atoms. The acyl group substitution degree is preferably in the range of 2.00 to 3.00, and more preferably in the range of 2.40 to 2.97. The lower the acyl group substitution degree, the higher the haze value tends to be (lower transparency), and the higher the water absorption and the lower the strength. Also, the lower the acyl group, the more likely sagging will occur due to stretching and deformation of the film due to water absorption when used for agricultural purposes, as in the present invention. For this reason, in the present invention, the acyl group substitution degree of the cellulose acylate is set to 2.00 or higher. Furthermore, a higher acyl group substitution degree results in lower water absorption, making it less likely for the film to stretch and deform due to water absorption, allowing for a lower average water content of the film and improving carbon dioxide retention. Furthermore, while the theoretical upper limit for the degree of acyl group substitution is 3.00, cellulose acylates with a degree of acyl group substitution exceeding 2.97 are difficult to synthesize, so it is more preferable to use a degree of 2.97 or less.

[0017] The degree of acyl group substitution of cellulose acylate is more preferably in the range of 2.40 to 2.97, and even more preferably in the range of 2.60 to 2.95. The degree of acyl group substitution can be measured in accordance with ASTM-D817-96, a standard set by the ASTM (American Society for Testing and Materials).

[0018] The degree of acyl group substitution can also be measured by measuring the degree of acylation (degree of acyl group substitution) distribution using high-performance liquid chromatography. As an example of this method, the degree of acetylation of cellulose acetate is measured by dissolving the sample in methylene chloride and using a Nova-Pak® phenyl column (manufactured by Waters Corporation) to measure the degree of acetylation distribution by a linear gradient from a methanol-water mixture (methanol:water mass ratio of 8:1) to a dichloromethane-methanol mixture (dichloromethane:methanol mass ratio of 9:1), and then comparing it with a calibration curve using standard samples with different degrees of acetylation. These measurement methods can be obtained by referring to the method described in Japanese Patent Publication No. 2003-201301. Furthermore, if the sample contains acyl groups with 3 or more carbon atoms, protons are used. １ It can also be measured by the 1H-NMR method. For example, in the case of cellulose acetate propionate, it can be dissolved in deuterated chloroform. １ By measuring the 1H-NMR spectrum, the protons are attributed to three groups: the pyranose ring proton derived from the cellulose unit, the combined methylene proton of the propionyl group and the methylene proton of the acetyl group, and the methyl proton of the propionyl group. The degree of substitution between the propionyl and acetyl groups can then be determined from the proton ratio. When measuring the degree of acetylation (degree of acetyl group substitution) of cellulose acylate, if the sample is taken from the cellulose acylate film 23, high-performance liquid chromatography is preferred due to the presence of additives. Alternatively, the degree of propionylation (degree of propionyl group substitution) of cellulose acylate can be measured by high-performance liquid chromatography, or... １ Measurement by 1H-NMR is preferred. By appropriately combining these measurement methods, several degrees of acyl group substitution can be determined.

[0019] The acyl substituent included in the cellulose acylate is preferably one that substitutes for a hydroxyl group in cellulose and has three or more carbon atoms. This is because having three or more carbon atoms in the acyl substituent reduces the water absorption of the agricultural film, making it less prone to stretching and deformation due to water absorption, improving carbon dioxide retention, and increasing transparency. The acyl group having three or more carbon atoms may be an aliphatic group or an aryl group, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, or aromatic alkyl carbonyl esters of cellulose, and these may each have further substituted groups. Examples of acyl substituents with three or more carbon atoms include propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, and cinnamoyl group. Preferably, the acyl substituents with three or more carbon atoms are propionyl group and butyryl group, and particularly preferably propionyl group.

[0020] The cellulose acylate may have only one type of acyl group or two or more types, but it is preferable that at least one type be an acetyl group. This is because having at least one acetyl group increases the transparency of the agricultural film.

[0021] The cellulose acylate has a weight-average molecular weight Mw in the range of 50,000 to 200,000, preferably in the range of 60,000 to 190,000, and more preferably in the range of 65,000 to 188,000. Furthermore, the cellulose acylate preferably has a dispersion degree expressed as Mn / Mw, which is the ratio of weight-average molecular weight Mw to quantity-average molecular weight Mn, in the range of 2 to 4. More preferably in the range of 2.2 to 3.5, and even more preferably in the range of 2.4 to 3.2.

[0022] Table 1 will be used to explain specific examples of cellulose acylate.

[0023]

[0024] In this embodiment, CAP, CAB, and CA-1, as shown in Table 1, are used as cellulose acylates. The degree of acyl group substitution, acetyl group substitution, propionyl group substitution, butyryl group substitution, weight-average molecular weight Mw, quantity-average molecular weight Mn, and dispersion (Mn / Mw) of CAP, CAB, and CA-1 are as shown in Table 1. CAP is used in Examples 1-6, 8-14, and Comparative Example 1 below, CAB is used in Example 7, and CA-1 is used in Comparative Example 2 below. Alternatively, cellulose ester resin from Tomoe Industries Co., Ltd. may be used as the cellulose acylate.

[0025] The polyester contained in the agricultural film of the present invention is preferably of general formula (1) or general formula (2) with a weight-average molecular weight of 50,000 to 1,000,000. For example, it is preferable to use biodegradable polyester (FD92) from Mitsubishi Chemical Corporation as the polyester. Polycaprolactone can also be used.

[0026] In formula (1) above, R1 and R2 are each alkyl groups, which may be the same or different from each other, and n is an integer of 1 or more. R1 is preferably a residue derived from a diol having 2 to 6 carbon atoms, and more preferably has 4 to 6 carbon atoms. R2 is preferably a residue derived from a dicarboxylic acid having an aliphatic group having 2 to 6 carbon atoms. Furthermore, it is more preferable that there are two or more types of R1 and / or R2. Also, in formula (2) above, R is an alkyl group, and n is an integer of 1 or more. R3 is preferably a residue derived from a dicarboxylic acid having 2 to 6 carbon atoms, and more preferably has 4 to 6 carbon atoms.

[0027] By incorporating the polyester described above into the agricultural film of the present invention, it is possible to achieve high transparency and low haze, and to appropriately increase the polyester content in the agricultural film, thereby imparting flexibility to the agricultural film and improving bending resistance. R1 is preferably a butanediol residue, and R2 is preferably one type of succinic acid residue, or two types of residues, succinic acid and adipic acid. This is polybutylene succinate-co-adipate (PBSA). Therefore, in formula (1), it is preferable that at least one of R1 and R2 is copolymerized from two or more different aliphatic molecules. Specifically, as the polyester, polybutylene succinate (PBS) or polybutylene succinate-adipate (PBSA) can be used.

[0028] The polyester has a weight-average molecular weight (Mw) in the range of 50,000 to 1,000,000, preferably in the range of 60,000 to 500,000, and more preferably in the range of 90,000 to 200,000. By using such a polyester with a relatively high molecular weight, tear strength and other properties can be improved.

[0029] Furthermore, it is preferable that the dispersion of the polyester, expressed as Mn / Mw (the ratio of weight-average molecular weight Mw to quantity-average molecular weight Mn), is within the range of 1 to 20. More preferably, it is within the range of 1.5 to 19, and even more preferably, within the range of 1.8 to 18.8. When the dispersion is within this range, it has a broad molecular weight distribution, which can suppress haze and improve bending resistance and tear strength.

[0030] The polyester content is preferably in the range of 30 parts by mass to 120 parts by mass, and more preferably in the range of 40 parts by mass to 110 parts by mass, per 100 parts by mass of cellulose acylate. Having polyester in the range of 30 parts by mass to 120 parts by mass suppresses haze and improves hardness and tear strength.

[0031] Table 2 will be used to explain specific examples of polyester.

[0032]

[0033] As the polyester, in this embodiment, as shown in Table 2, additive A was used in Examples 1 to 14 and Comparative Example 1, and additive C was used in Comparative Example 2. Additive A is PBS, specifically FD92 manufactured by Mitsubishi Chemical Corporation. Additive B is polycaprolactone. The quantity-average molecular weight Mn, weight-average molecular weight Mw, and dispersion (Mn / Mw) values ​​of additives A and B, as well as the components of R1, R2 (first component only), R, and the ratio of the first and second components when R2 consists of two first and second components, are shown in Table 2. The molecular weights (Mw, Mn) were determined by gel permeation chromatography (GPC).

[0034] The agricultural film of the present invention preferably has a contact angle of 50 degrees or less, more preferably 55 degrees or less, on at least one of the film surfaces. To achieve a contact angle of 50 degrees or less, for example, the agricultural film of the present invention may have a hydrophilic layer (see hydrophilic layer 11 in Figure 1) in addition to the layer containing cellulose acylate and polyester (see first layer 10 in Figure 1), or a hydrophilizing agent may be added to the layer containing cellulose acylate and polyester (first layer 10 in Figures 2 to 4). By setting the contact angle to 50 degrees or less, a water film is easily formed and the film appears transparent, while if the contact angle exceeds 50 degrees, a water film is difficult to form and the film appears opaque overall.

[0035] The hydrophilic layer is preferably formed by saponification of the layer containing cellulose acylate and polyester. Saponification can be carried out by contacting the layer containing cellulose acylate with an aqueous solution of sodium hydroxide and / or potassium hydroxide. The saponification solution preferably contains alkali and water, as well as one or more organic solvents selected from the group consisting of alcohols, ethers, amides, and sulfoxides. By including an organic solvent, the hydrophilic layer can be formed thicker than the layer containing cellulose acylate, and the water absorption of the hydrophilic layer can be increased.

[0036] As for alcohols, those with 2 to 8 carbon atoms are preferred. Examples of alcohols with 2 to 8 carbon atoms include ethanol, isopropyl alcohol, 1-propanol, 1-butanol, hexanol, ethylene glycol, glycerin, propylene glycol, butylene glycol, and pentaerythritol. Among these, ethanol and isopropyl alcohol are particularly preferred. As for ethers, ethers with 2 to 10 carbon atoms and containing at least one hydroxyl group are preferred. Examples include diethylene glycol, dipropylene glycol, triethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, and diethylene glycol monoethyl ether acetate. Among these, diethylene glycol monoethyl ether and propylene glycol monomethyl ether are particularly preferred. Examples of amides include N,N-dimethylformamide and dimethylacetamide. Examples of sulfoxides include dimethyl sulfoxide.

[0037] The hydrophilic layer can be produced by coating or immersion methods. The saponification treatment by immersion can be carried out under any conditions, but for example, it may include a saponification step, a first washing step, a neutralization step, a second washing step, and a drying step. In the saponification step, the film is immersed in an alkaline aqueous solution to saponify the film surface. As the alkali, for example, sodium hydroxide (NaOH) or potassium hydroxide (KOH) is used. The saponification solution contains ethanol. In the first washing step, the film that has gone through the saponification step is washed. Washing is performed, for example, with pure water. In the neutralization step, an acid or an aqueous solution of acid is used as the neutralizing solution, and the film that has gone through the first washing step is neutralized with this neutralizing solution. In the second washing step, the film that has gone through the neutralization step is washed, for example, with pure water. In the drying step, the film that has gone through the second washing step is dried. On the side where a hydrophilic layer is not needed, it is possible to prevent the formation of a hydrophilic layer on one side by laminating a protective film or other method.

[0038] Furthermore, to form a hydrophilic layer, a hydrophilizing agent can be added to a layer containing cellulose acylate, or to a layer containing cellulose acylate and polyester. The hydrophilizing agent added to the layer containing cellulose acylate, or to the layer containing cellulose acylate and polyester, is preferably a long-chain alkyl sulfonic acid. The long-chain alkyl sulfonic acid is an alkyl sulfonate compound, and for example, Chemistat 3033 from Sanyo Chemical Industries, Ltd. is preferred. Chemistat 3033 has a relatively simple structure consisting of an alkane with 10 to 12 carbon atoms and sodium sulfonate (a mixture of different molecular weights).

[0039] Furthermore, the hydrophilizing agent content is preferably in the range of 1 to 10 parts by mass, and more preferably in the range of 2 to 5 parts by mass, per 100 parts by mass of cellulose acylate. By using the above content, the transparency of the agricultural film can be kept high and the contact angle can be made 50 degrees or less.

[0040] Incidentally, as the hydrophilic agent, a silicone antifogging agent having a structure in which a polyether group is introduced at the terminal or side chain of a silicone chain may be used, and the general formula (3) may be used. This is because the hydrophobic silicone chain increases the concentration of the antifogging agent on the surface of the agricultural film, and at the same time, the hydrophilic polyether group can exhibit antifogging properties. As the silicone antifogging agent, for example, it is preferable to use SAG-500, SAG-005, and SAG-008 of Silface (registered trademark) of Nissin Chemical Industry Co., Ltd. Also, BYK (registered trademark) 346, 347, 348, 349, etc. of BYK Japan Co., Ltd. can also be used.

[0041] In the above formula (3), R4 and R5 are each a polyether group, and n is an integer of 1 or more.

[0042] Incidentally, Fig. 11(A) shows the time-series data of the contact angle when pure water is dropped onto one surface of an agricultural film not containing a silicone antifogging agent, and Fig. 11(B) shows the time-series data of the contact angle when pure water is dropped onto one surface of an agricultural film containing a silicone antifogging agent. When the agricultural film does not contain a silicone antifogging agent, the contact angle is 50 degrees or more even after a certain period has elapsed 1 minute (60 seconds) after dropping pure water. On the other hand, when the agricultural film contains a silicone antifogging agent, the contact angle is less than 50 degrees 1 minute (60 seconds) after dropping pure water.

[0043] The agricultural film of the present invention preferably has an equilibrium moisture content of 2% or less, more preferably 1% or less, at 25°C and 80% RH. Thereby, the moisture content in the use environment of the agricultural film can be suppressed, and the carbon dioxide retention property can be improved. Also, the agricultural film of the present invention preferably has a folding resistance of 500 or more times, more preferably 1000 or more times. Thereby, breakage can be suppressed and good flexibility can be obtained.

[0044] The agricultural film of the present invention is preferably an agricultural film 12 having a first layer 10 containing cellulose acylate and polyester, and a hydrophilic layer 11 with a contact angle of 50 degrees or less, as shown in Figure 1. In Figure 1, the hydrophilic layer 11 is preferably a layer formed by saponification treatment. For the agricultural film 12, the thickness T1 of the first layer is preferably 50 μm or more and 150 μm or less, and more preferably 70 μm or more and 120 μm or less. On the other hand, the thickness Th of the hydrophilic layer 11 is preferably about 0.01 μm to 10 μm. The hydrophilic layer 11 can be detected by whether or not it remains as an insoluble component in the dichloromethane solution when a sample taken from the agricultural film 12 is immersed in dichloromethane for 24 hours. Furthermore, the thickness of the hydrophilic layer 11 can be determined by methods such as drying the sample that remains undissolved after dichloromethane immersion and measuring the thickness of the dried sample, or by correlating the thickness of the hydrophilic layer after dichloromethane immersion with the ATR method of FT-IR.

[0045] Furthermore, as shown in Figure 2, the agricultural film of the present invention is preferably an agricultural film 14 having a first layer 10 containing cellulose acylate, polyester, and a hydrophilizing agent to set the contact angle to 50 degrees or less. For the agricultural film 14, the thickness T1 of the first layer 10 is preferably 50 μm or more and 150 μm or less, and more preferably 70 μm or more and 120 μm or less.

[0046] Furthermore, as shown in Figure 3, the agricultural film of the present invention is preferably an agricultural film 18 having a first layer 10 containing cellulose acylate and a hydrophilizing agent for making the contact angle 50 degrees or less, and a second layer 16 containing cellulose acylate and polyester. For the agricultural film 18, the thickness T1 of the first layer 10 is preferably 5 μm or more and 25 μm or less, and more preferably 8 μm or more and 22 μm or less. On the other hand, the thickness T2 of the second layer 16 is preferably 40 μm or more and 140 μm or less, and preferably 60 μm or more and 100 μm or less.

[0047] Furthermore, as shown in Figure 4, the agricultural film of the present invention is preferably an agricultural film 20 having a first layer 10 containing cellulose acylate, polyester, and a hydrophilizing agent to set the contact angle to 50 degrees or less, and a second layer 16 containing cellulose acylate and polyester. The thickness of the agricultural film 20 may be the same as or different from the thickness of the first layer 10 or the second layer 16 of the agricultural film 18.

[0048] The agricultural film of the present invention is preferably used as an agricultural covering material. Specifically, it is preferably used as an agricultural covering material, as a film to cover various agricultural products cultivated in an agricultural covering body. As shown in Figure 5, the agricultural covering body 22 includes an agricultural film 24 that is at least positioned on the upper part 22a and covers the plant body PL that stands upright from the plant bed, and a ventilation pipe 26 that supplies carbon dioxide-enriched air to the inside of the agricultural covering body 22. The agricultural covering body 22 also has ventilation openings 27 provided on the inside of the agricultural covering body 22 that can adjust temperature and humidity. The agricultural film 24 is one of the above agricultural films 12, 14, 18, and 20, or a combination of two or more of them. In Figures 7 to 9, ventilation pipes 26 and ventilation openings 27 are also provided, but are not shown.

[0049] In the agricultural covering 22, as shown in Figure 6, multiple plant bodies PL are planted in the cultivation container 28 at regular intervals. The cultivation container 28 is preferably for hydroponics or soil cultivation. To ensure that carbon dioxide is evenly supplied to the multiple plant bodies PL arranged in the cultivation container 28, the ventilation pipe 26 is provided below the cultivation container 28, along the direction in which the plant bodies PL are arranged in the cultivation container 28. In addition, the ventilation openings 27 are located inside the agricultural covering 22, at the same position as or slightly above the plant bodies PL, so that the temperature or humidity inside the agricultural covering 22 can be adjusted by ventilating the air inside the agricultural covering 22.

[0050] By providing a highly light-transmitting agricultural film 24 on the upper part 22a of the agricultural covering 22, which is most easily exposed to sunlight, and by supplying carbon dioxide-enriched air to the interior through the ventilation pipe 26, the efficiency of carbon dioxide utilization by plant PL can be increased, and the efficiency of using carbon dioxide-enriched air can be improved. Furthermore, by providing the agricultural film 24 on the upper part 22a of the agricultural covering 22, tearing can be suppressed, and moisture permeability, drip-free (water droplets do not easily drip) and carbon dioxide retention can be obtained. In addition, by adjusting the angle of the agricultural film 24 provided on the upper part 22a with respect to the ground, for example, by tilting it slightly from a horizontal position relative to the ground, water droplets can flow more easily and form a water film, improving drip-free and light-transmitting properties. Furthermore, by providing temperature and humidity control functions inside the agricultural covering 22, improved heating and cooling efficiency and reduced energy consumption can be achieved.

[0051] By also placing a highly light-transmitting agricultural film 24 on the side portion 22b of the plant body PL, a large amount of sunlight reaches the entire plant body PL, further promoting photosynthesis in the plant body PL. In addition, by providing the agricultural film 24 on the side portion 22b, it offers excellent moisture permeability, drip resistance (water droplets are less likely to drip), carbon dioxide retention, and ease of handling such as folding and rolling, thus improving raising and lowering and opening and closing.

[0052] Furthermore, in the agricultural covering 22, the agricultural film 24 may be rolled up or unrolled in accordance with the growth of the plant PL. Since the agricultural film 24 is suitable for handling by rolling it up or folding it, the agricultural covering 22 can be made more compact in accordance with the growth and harvest of the plant PL, thus increasing the flexibility of the covering space.

[0053] Specifically, as shown in Figures 7(A) and (B), the agricultural covering 22 may cover the plant body PL with a height-adjustable film section 30 and a height-fixed film section 31. The height-adjustable film section 30 has an agricultural film 24 and its height can be changed. The height-adjustable film section 30 includes a fixed roll 30a and a plurality of movable rollers 30b, and the fixed roll 30a and the plurality of movable rollers 30b are arranged so that the agricultural film 24 covers the plant body PL according to its height. The height-fixed film section 31 has an agricultural film 24 and its height is fixed. The height-fixed film section 31 arranges the agricultural film 24 in a curtain-like manner at the maximum height to which the plant body PL can grow. The distance between the height-adjustable film section 30 and the height-fixed film section 31 can be adjusted or a cover can be added, taking into consideration carbon dioxide retention, etc.

[0054] As shown in Figure 7(A), when the height of the plant body PL is small, the height of the movable roller 30b is lowered, and as shown in Figure 7(B), when the height of the plant body PL is large, the height of the movable roller 30b is raised, thereby raising the position of the agricultural film 24 covering the plant body PL. In this case, changing the height of the movable roller 30b also changes the position of the agricultural film 24 supported by the movable roller 30b. Even if the position supported by the movable roller 30b changes in this way, the agricultural film 24 has sufficient bending strength and flexibility, so it is possible to easily and smoothly change the covering space of the plant body PL while suppressing tearing of the agricultural film 24. Furthermore, by using a height-adjustable film section 30 and a height-fixed film section 31 for covering the plant body PL, it is possible to change the height of only a part of the height-adjustable film section 30 and leave the height of the other height-fixed film sections 31 unchanged, thus reducing the effort required to adjust the height of the agricultural film 24.

[0055] Furthermore, as shown in Figures 8(A) and 8(B), the entire height-adjustable film section 33 of the agricultural covering 22 may cover the plant body PL. The height-adjustable film section 33 has an agricultural film 24 and its height can be changed. The height-adjustable film section 33 has a movable roller 33a, and the movable roller 33a is positioned so that the agricultural film 24 is covered according to the height of the plant body PL. As shown in Figure 8(A), when the height of the plant body PL is small, the height of the movable roller 33a is lowered, and as shown in Figure 8(B), when the height of the plant body PL is large, the height of the movable roller 33a is raised, thereby raising the position of the agricultural film 24 covering the plant body PL.

[0056] As described above, even if the position supported by the movable roller 33b changes, the agricultural film 24 has sufficient bending strength and flexibility, so that the covering space of the plant body PL can be changed easily and smoothly while suppressing tearing of the agricultural film 24. In Figure 8, if the length in the height direction of the agricultural film is kept constant to match the maximum possible growth length, when the height of the plant body PL is low, the excess portion of the agricultural film 24 in the height direction will be twisted.

[0057] Furthermore, as shown in Figure 9, an agricultural covering 22 that covers the plant body PL may be placed inside the agricultural greenhouse 35. By covering the plant body PL with a double greenhouse consisting of the agricultural covering 22 and the agricultural greenhouse 35, it is possible to achieve both the protective function of the large agricultural greenhouse 35 (protection of plants from natural disasters such as typhoons and heavy rains) and the environmental control function of the agricultural covering 22 (moisture permeability, drip resistance, and carbon dioxide retention). Specifically, compared to enriching the entire agricultural greenhouse with carbon dioxide and providing air conditioning (opening windows, etc.), supplying air with a high carbon dioxide concentration or providing air conditioning for each agricultural covering 22 can suppress carbon dioxide loss and energy loss.

[0058] The following describes embodiments of the present invention.

[0059] [Examples 1-7] CAP as cellulose acylate and additive A as polyester were mixed in a twin-screw kneading extruder and extruded to form pellets. As shown in Figure 10, the pelletized material was fed into an extruder 40 and melted. The molten material was extruded from a cylindrical die 41 to form a tubular film 42. Simultaneously, gas was blown into the center of the cylindrical die 41 to expand the tubular film 42. Gas was blown from an air ring (cooling ring) 44 toward the outside of the tubular film 42 extruded from the cylindrical die 41 to cool and solidify the discharged molten material. One end of the tubular film 42 was cut off to form a single sheet. Thus, a single sheet was obtained by melt film formation. In Example 7, CAB was used instead of CAP, and the procedure was carried out in the same manner as in Examples 1-6.

[0060] Then, saponification was performed on one side of a sheet after melt-forming to form a hydrophilic layer. Saponification was carried out by immersion, with a water-to-ethanol ratio of 75:25. Specifically, the sheet was immersed in a saponification solution consisting of 1.5 mol / L NaOH, water, and ethyl alcohol in a 75:25 ratio, at a liquid temperature of 55°C for an adjusted immersion time. After that, as a washing step, the sheet was immersed in pure water at a temperature of 25°C for 60 seconds. This formed the agricultural films of Examples 1 to 7. The agricultural films of Examples 1 to 7 consist of a first layer containing cellulose acylate and polyester, and a hydrophilic layer. The type and mass of cellulose acylate, the type and mass of polyester, the thickness of the first layer, and the presence or absence of the hydrophilic layer are shown in Table 3.

[0061] [Examples 8-10] When manufacturing a single sheet by melt film formation, in addition to CAP as cellulose acylate and polyester, chemistat 3033 as a hydrophilic agent was added to obtain a pellet-shaped processed product. Otherwise, a single sheet was obtained by melt film formation in the same manner as in Examples 1-7. This yielded the agricultural films of Examples 8-10. The agricultural films of Examples 8-10 consist only of a first layer containing cellulose acylate, polyester, and a hydrophilic agent. The type and parts by mass of cellulose acylate, the type and parts by mass of polyester, the type and parts by mass of the hydrophilic agent, and the thickness of the first layer are shown in Table 3.

[0062] [Examples 11, 12] When manufacturing one sheet by melt deposition, CAP as cellulose acylate and Chemistat 3033 as a hydrophilic agent were added to obtain a pellet-shaped processed material for the first layer, and CAP and polyester were added to obtain a pellet-shaped processed material for the second layer. Then, using the pellet-shaped processed material for the first layer and the pellet-shaped processed material for the second layer, one sheet was obtained by melt deposition in the same manner as in Examples 1 to 7. This obtained the agricultural films of Examples 11 and 12. The agricultural films of Examples 11 and 12 consist of a first layer containing cellulose acylate and a hydrophilic agent, and a second layer containing cellulose acylate and polyester. The type of cellulose acylate, parts by mass, type of hydrophilic agent, parts by mass, and thickness of the first layer in the first layer, and the type of cellulose acylate, parts by mass, type of polyester, parts by mass, and thickness of the second layer in the second layer are as shown in Table 3.

[0063] [Examples 13, 14] When manufacturing one sheet by melt film formation, CAP as cellulose acylate, polyester, and the hydrophilic agent Chemistat 3033 were added to obtain a pellet-shaped processed material for the first layer, and CAP and polyester were added to obtain a pellet-shaped processed material for the second layer. Then, using the pellet-shaped processed material for the first layer and the pellet-shaped processed material for the second layer, one sheet was obtained by melt film formation in the same manner as in Examples 1 to 7. This obtained the agricultural films of Examples 13 and 14. The agricultural films of Examples 13 and 14 consist of a first layer containing cellulose acylate, polyester, and a hydrophilic agent, and a second layer containing cellulose acylate and polyester. The type and parts by mass of cellulose acylate in the first layer, the type and parts by mass of polyester, the type and parts by mass of hydrophilic agent, the thickness of the first layer, the type and parts by mass of cellulose acylate in the second layer, the type and parts by mass of polyester, and the thickness of the second layer are as shown in Table 3.

[0064] [Examples 15, 16] When manufacturing one sheet by melt film formation, CAP as cellulose acylate, polyester, and the hydrophilic agent SAG-005 were added to obtain a pellet-shaped processed material for the first layer, and CAP and polyester were added to obtain a pellet-shaped processed material for the second layer. Then, using the pellet-shaped processed material for the first layer and the pellet-shaped processed material for the second layer, one sheet was obtained by melt film formation in the same manner as in Examples 1 to 7. This obtained the agricultural films of Examples 15 and 16. The agricultural films of Examples 15 and 16 consist of a first layer containing cellulose acylate, polyester, and a hydrophilic agent, and a second layer containing cellulose acylate and polyester. The type and parts by mass of cellulose acylate in the first layer, the type and parts by mass of polyester, the type and parts by mass of hydrophilic agent, the thickness of the first layer, the type and parts by mass of cellulose acylate in the second layer, the type and parts by mass of polyester, and the thickness of the second layer are as shown in Table 3.

[0065] [Comparative Example 1] A single sheet was obtained by melt-forming using the same method as in Examples 1 to 7. The single sheet after melt-forming was used as the agricultural film for Comparative Examples 1 and 2. The agricultural film consists only of a first layer containing CAP as cellulose acylate and polyester. The type and parts by mass of cellulose acylate, the type and parts by mass of polyester, and the thickness of the first layer are as shown in Table 3. Unlike Examples 1 to 7, no hydrophilic layer was formed.

[0066] [Comparative Example 2] In Comparative Example 2, the cellulose acylate was CA-1 and the polyester was additive C, except that the procedure was the same as in Comparative Example 1.

[0067] The evaluation results for the agricultural films obtained in each example and comparative example are shown in Table 3. Contact angle, water film formation, haze, elastic modulus, flexural strength, equilibrium water content, and moisture permeability were evaluated using the following methods.

[0068] <Contact Angle> Agricultural films were conditioned at 25°C and 60% relative humidity (RH) for more than one hour, and the contact angle of the agricultural film with respect to pure water was measured. The contact angle was taken as the value 15 seconds after dropping pure water. A fully automatic contact angle meter DMo-902 from Kyowa Interface Science Co., Ltd. was used to measure the contact angle. In Examples 1, 15, and 16, in addition to the value 15 seconds after dropping pure water, the contact angle was also taken as the value 60 seconds after dropping pure water.

[0069] <Formation of Water Film> A 5cm x 30cm agricultural film was placed on a 40°C water bath at a 45-degree angle and left for 10 minutes. When a water film formed on the agricultural film, it appeared transparent to the naked eye, while the areas where the film did not form appeared cloudy. Based on the area ratio of the water film formed, the following evaluations were made: A: A water film formed on 50% to 100% of the test area, making the entire surface appear transparent. B: A water film formed on 20% to 50% of the test area, making most of the surface appear transparent. C: A water film formed on less than 20% of the test area, making the entire surface appear opaque.

[0070] <Haze> The degree of haze was evaluated using the NDH5000 haze meter from Nippon Denshoku Industries, Ltd., as one of the values ​​representing total light transmittance.

[0071] <Module of Elasticity> The tensile modulus of elasticity was measured in accordance with the Japanese Industrial Standard JIS K7161:2014 under the following conditions. Specifically, eight test pieces were prepared from agricultural film, each 150 mm long and 15 mm wide, with the cutting direction of the measurement direction varied by 45° increments. The test pieces were stretched with a chuck length of 100 mm and a tensile strength of 200 mm / min under conditioning and a test atmosphere of 25°C and 60% RH. The strain was measured at elongation of 0.1% and 0.5%, and the modulus of elasticity was calculated from the slope of the strain at two points. The modulus of elasticity was then calculated by averaging these values. A tensile testing machine (manufactured by A&D Co., Ltd.) was used as the measuring instrument.

[0072] <Folding Strength> Folding strength was determined by the MIT test method. A No. 530 MIT folding strength tester manufactured by Toyo Seiki Co., Ltd. was used. A test specimen with a width of 15 mm x length of 110 mm was subjected to a load of 9.8 N, and the test was performed at a 135-degree angle on both sides of a bending surface with a radius of curvature R0.38, and the number of passes until breakage was determined.

[0073] <Equilibrium Moisture Content> After humidifying agricultural film at 25°C and 80% RH for 24 hours, 500 mg was measured using a Karl Fischer moisture meter (AQ-2200) manufactured by Hiranuma Sangyo Co., Ltd.

[0074] <Moisture Permeability> The moisture permeability test was conducted using a moisture permeability cup specified by JIS, in an environment of 40°C and 90% RH, and evaluated according to the Japanese Industrial Standard JIS Z-0208.

[0075]

[0076] 10 First layer 11 Hydrophilic layer 12, 14, 18, 20, 24 Agricultural film 16 Second layer 22 Agricultural covering 22a Top 22b Side 26 Ventilation pipe 27 Ventilation opening 28 Cultivation container 30, 33 Height-adjustable film section 30a Fixed roll 30b, 33a Movable roller 31 Height-fixed film section 35 Agricultural greenhouse 40 Extruder 41 Cylindrical die 42 Tubular film 44 Air ring PL Plant body T1, Th, T2 Thickness

Claims

1. An agricultural film comprising a cellulose acylate having an acyl group substitution degree of 2 or more and at least one acyl substituent with 3 or more carbon atoms, and a polyester of general formula (1) or general formula (2) having a weight-average molecular weight of 50,000 to 1,000,000, wherein the contact angle of at least one film surface is 50 degrees or less. In formula (1), R1 and R2 are each alkyl groups, which may be the same or different, and n is an integer of 1 or more. In formula (2), R3 is an alkyl group, and n is an integer of 1 or more.

2. The agricultural film according to claim 1, wherein the equilibrium moisture content at 25°C and 80% RH is 2% or less.

3. The agricultural film according to claim 1, wherein the folding strength is 500 times or more.

4. The agricultural film according to claim 1, comprising a first layer containing the cellulose acylate and the polyester, and a hydrophilic layer having a contact angle of 50 degrees or less.

5. The agricultural film according to claim 1, further comprising a hydrophilizing agent for making the contact angle 50 degrees or less.

6. The agricultural film according to claim 5, wherein the hydrophilic agent is a long-chain alkyl sulfonic acid.

7. The contact angle becomes 50 degrees or less 1 minute after dropping pure water, and the hydrophilizing agent is a silicone drip agent having a structure in which polyether groups are introduced to the ends or side chains of a silicone chain, as described in claim 5.

8. The agricultural film according to claim 5, having a first layer comprising the cellulose acylate, the polyester, and the hydrophilic agent.

9. The agricultural film according to claim 5, comprising a first layer containing the cellulose acylate and the hydrophilizing agent, and a second layer containing the cellulose acylate and the polyester.

10. The agricultural film according to claim 5, comprising a first layer containing the cellulose acylate, the polyester, and the hydrophilizing agent, and a second layer containing the cellulose acylate and the polyester.

11. An agricultural covering material using the agricultural film described in claim 1.

12. An agricultural covering comprising an agricultural film according to any one of claims 1 to 10, which is provided at least at the top and covers a plant body standing upright from a plant bed, wherein the agricultural covering has a ventilation pipe that supplies carbon dioxide-enriched air to the inside of the agricultural covering.

13. The agricultural covering according to claim 12, wherein the agricultural film is arranged on the side surface of the agricultural covering.

14. The agricultural covering according to claim 12, which has a ventilation opening on the inside of the agricultural covering that can adjust temperature and humidity.

15. The agricultural covering according to claim 12, comprising: a height-adjustable film portion having the agricultural film and whose height can be changed; and a height-fixed film portion having the agricultural film and whose height is fixed, wherein the plant body is covered by the height-adjustable film portion and the height-fixed film portion.

16. The agricultural covering according to claim 12, which has the agricultural film and a height-adjustable film portion whose height can be changed, wherein the plant body is covered with the height-adjustable film portion.

17. The agricultural covering body according to claim 12, which is placed inside an agricultural greenhouse.

Images