Sheet, cover, and bag

Abstract

A sheet comprising a base material formed from a resin, wherein the base material has a thickness of 20-300 μm, the base material has a plurality of ventilation holes penetrating the front and rear of the base material, the equivalent circle diameter of each of the plurality of ventilation holes is 0.10-0.50 mm, and the pitch between the centers of adjacent ventilation holes is 5-30 mm.

Description

Sheets, covers, and bags

[0001] The present invention relates to sheets, covers, and bags.

[0002] Patent Document 1 discloses a fruit bag for protecting fruit from rain and sunburn during fruit tree cultivation. This fruit bag is made of a resin film. This resin film has a transmittance of 540 nm and 850 nm, respectively. ５４０ , and T ８５０ In that case, T ８５０ / T ５４０ The value is 0.85 or less, and the water vapor transmission rate at 40°C and 90% RH is 100 to 2000 g / (m³). ２ It is a day.

[0003] Japanese Patent Publication No. 2020-005563

[0004] Protective sheets for fruit require both breathability and water-repellent properties. Covering fruit with a sheet reduces breathability, increasing humidity around the fruit and making it susceptible to disease due to mold or fungal growth. Protective sheets for fruit must be able to withstand rain and condensation. There is still room for improvement in terms of adequate breathability and water-repellent properties for protective sheets for fruit.

[0005] One object of the present invention is to provide a sheet that achieves both sufficient breathability and water leakage prevention properties. Another object of the present invention is to provide a cover that achieves both sufficient breathability and water leakage prevention properties. Another object of the present invention is to provide a bag that achieves both sufficient breathability and water leakage prevention properties.

[0006] (1) A sheet according to one embodiment of the present invention comprises a base material made of resin. The thickness of the base material is 20 μm or more and 300 μm or less. The base material has a plurality of ventilation holes that penetrate through the front and back surfaces of the base material. The equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less.

[0007] The sheet described in (1) above has excellent breathability and water leakage prevention properties. Breathability means that air can easily move between the front and back surfaces of the sheet through the ventilation holes. Water leakage prevention means that water cannot easily pass from the front surface to the back surface of the sheet through the ventilation holes.

[0008] (2) In the sheet described in (1) above, the contact angle of the base material may be 65° or more or 40° or less, and the equivalent diameter of each of the plurality of ventilation holes may be 0.18 mm or more or 0.22 mm or less.

[0009] The contact angle of the substrate is the angle formed between the surface of the substrate and the surface of the water. The sheet described in (2) above is superior in both breathability and water leakage prevention properties. With the sheet described in (2) above, water flowing along the substrate has difficulty entering the inside of the ventilation holes, and even when water hits the substrate strongly due to wind and rain and water pressure is applied, water has difficulty entering the inside of the ventilation holes.

[0010] (3) In the sheet described in (1) above, the thickness of the base material may be 90 μm or more, the contact angle of the base material may be greater than 40° and less than or equal to 65°, and the equivalent diameter of each of the plurality of ventilation holes may be 0.18 mm or more and 0.22 mm or less.

[0011] The sheet described in (3) above is superior in both breathability and water leakage prevention properties. With the sheet described in (3) above, water flowing along the base material is less likely to enter the inside of the ventilation holes, and even when water hits the base material strongly due to wind and rain and water pressure is applied, water is less likely to enter the inside of the ventilation holes.

[0012] (4) In the sheet described in (1) above, the substrate may comprise a first surface layer, an intermediate layer, and a second surface layer in this order. The thickness of the substrate is 90 μm or more. The equivalent diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less. The contact angles of the first surface layer and the second surface layer are smaller than the contact angle of the intermediate layer.

[0013] When water comes into contact with the first surface layer, a film of water forms around the periphery of the vents formed in the first surface layer. If the contact angle of the first surface layer is smaller than the contact angle of the intermediate layer, that is, if the contact angle of the intermediate layer inside the vents is larger than the contact angle of the first surface layer, water will have more difficulty passing through the vents compared to when the contact angle of the first surface layer is equal to or greater than the contact angle of the intermediate layer. Therefore, in the sheet described in (4) above, water flowing along the first surface layer has difficulty entering the vents, and even when water strongly hits the substrate due to wind and rain, creating water pressure, water will have more difficulty passing through the vents. The same effect is achieved when water comes into contact with the second surface layer as when water comes into contact with the first surface layer.

[0014] In the case of the sheet described in (4) above, since the base material has a multi-layer structure, the shape of the sheet is more easily maintained over a long period of time even when subjected to water pressure from wind and rain.

[0015] (5) In any of the sheets described in (1) to (4) above, the base material may include at least one of polyethylene terephthalate resin and polypropylene resin.

[0016] Polyethylene terephthalate resin and polypropylene resin have high water resistance and high flexural strength. Water resistance means that they do not deteriorate easily even when wet. The sheet described in (5) above has excellent breathability and water leakage prevention properties, and the sheet's shape is easily maintained over the long term even when subjected to water pressure from wind and rain.

[0017] (6) In any of the sheets described in (1) to (5) above, the ratio of the total area of ​​the plurality of ventilation holes to a predetermined area of ​​the base material may be 0.02% or more and 0.20% or less.

[0018] The sheet described in (6) above easily achieves both sufficient breathability and water leakage prevention properties. The predetermined area of ​​the base material is, for example, 10 cm x 10 cm.

[0019] (7) In any of the sheets described in (1) to (5) above, the heat shielding rate of the base material may be 70% or more.

[0020] Covering the object to be covered with the sheet described in (7) above makes it easier to prevent the temperature of the object from rising.

[0021] (8) A cover according to one embodiment of the present invention is formed of a resin substrate. The thickness of the substrate is 20 μm or more and 300 μm or less. The substrate has a plurality of ventilation holes and notches. The plurality of ventilation holes penetrate through the front and back surfaces of the substrate. The equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less. The notches are provided from the periphery of the substrate toward the center. A cover according to one embodiment of the present invention has an umbrella shape formed by overlapping the peripheral portions of the notches. The substrate formed in the umbrella shape has a larger area than the object to be covered when viewed in the direction along the axis of the umbrella shape.

[0022] If the object to be covered is a fruit, the cover is fixed to a branch extending from the fruit, positioned to cover the top of the fruit. If the base material has notches, a branch can be inserted into the notches and the surrounding areas can be overlapped to easily create an umbrella-shaped cover over the top of the fruit. The area of ​​the object to be covered is the area viewed along the axis of the umbrella shape when the object is covered by the cover. Because the area of ​​the umbrella-shaped base material is larger than the area of ​​the object to be covered, the cover can protect the fruit from sunburn, rain, and pests that climb the branches.

[0023] (9) In the cover of (8) above, the contact angle of the outward-facing surface of the base material may be 65° or more or 40° or less, and the equivalent diameter of each of the plurality of ventilation holes may be 0.18 mm or more or 0.22 mm or less.

[0024] The cover described in (9) above provides the same effect as the sheet described in (2) above, in addition to the effect of the cover described in (8) above.

[0025] (10) In the cover of (8) above, the thickness of the base material may be 90 μm or more, the contact angle of the outward-facing surface of the base material may be greater than 40° and less than or equal to 65°, and the equivalent circular diameter of each of the plurality of ventilation holes may be 0.18 mm or more and 0.22 mm or less.

[0026] The cover described in (10) above provides the same effect as the sheet described in (3) above, in addition to the effect of the cover described in (8) above.

[0027] (11) In the cover of (8) above, the substrate may comprise a first surface layer, an intermediate layer, and a second surface layer in this order. The thickness of the substrate is 90 μm or more. The equivalent diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less. The contact angles of the first surface layer and the second surface layer are smaller than the contact angle of the intermediate layer.

[0028] The cover described in (11) above provides the same effect as the sheet described in (4) above, in addition to the effect of the cover described in (8) above.

[0029] (12) In any of the covers described in (8) to (11) above, the base material may include at least one of polyethylene terephthalate resin and polypropylene resin.

[0030] The cover described in (12) above provides the same effect as the sheet described in (5) above, in addition to the effect of the cover described in (8) above.

[0031] (13) In any of the covers described in (8) to (12) above, the ratio of the total area of ​​the plurality of ventilation holes to a predetermined area of ​​the base material may be 0.02% or more and 0.20% or less.

[0032] The cover described in (13) above provides the same effect as the sheet described in (6) above, in addition to the effect of the cover described in (8) above.

[0033] (14) In any of the covers described in (8) to (13) above, the heat shielding rate of the base material may be 70% or more.

[0034] The cover described in (14) above provides the same effect as the sheet described in (7) above, in addition to the effect of the cover described in (8) above.

[0035] (15) A bag according to one embodiment of the present invention is formed of a base material made of resin. The thickness of the base material is 20 μm or more. The base material has a plurality of ventilation holes that penetrate through the front and back surfaces of the base material. The equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less.

[0036] If the object to be stored in the bag is a fruit, the bag is fixed to the branch extending from the fruit at the opening of the bag in the state where the fruit is stored. By storing the fruit in the bag, the fruit can be protected from sunburn, rain, and pests transmitted through the branch.

[0037] (16) In the bag of (15) above, the contact angle of the surface facing outward in the base material may be 65° or more or 40° or less, and the equivalent circle diameter of each of the plurality of ventilation holes may be 0.18 mm or more and 0.22 mm or less.

[0038] The bag of (16) above exhibits the same effect as the sheet of (2) above in addition to the effect of the bag of (15) above.

[0039] (17) In the bag of (15) above, the base material may include a first surface layer, an intermediate layer, and a second surface layer in this order. The thickness of the base material is 90 μm or more and 300 μm or less. The equivalent circle diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less. The pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less. The contact angle of each of the first surface layer and the second surface layer is smaller than the contact angle of the intermediate layer.

[0040] The bag of (17) above exhibits the same effect as the sheet of (4) above in addition to the effect of the bag of (15) above.

[0041] (18) In any of the bags of (15) to (17) above, the base material may include at least one of polyethylene terephthalate resin and polypropylene resin.

[0042] The bag of (18) above exhibits the same effect as the sheet of (5) above in addition to the effect of the bag of (15) above.

[0043] (19) In any of the bags of (15) to (18) above, the ratio of the total area of the plurality of ventilation holes to the predetermined area of the base material may be 0.02% or more and 0.20% or less.

[0044] The bag of (19) above exhibits the same effect as the sheet of (6) above in addition to the effect of the bag of (15) above. )]]

[0045] (20) In any of the bags described in (15) to (19) above, the heat shielding rate of the base material may be 70% or more.

[0046] The bag described in (20) above has the same effect as the sheet described in (7) above, in addition to the effect of the bag described in (15) above.

[0047] (21) The cover of the present invention described above can be used in a method for growing fruit trees. For example, a method for growing fruit trees includes the step of fixing one of the covers described in (8) to (14) above to a branch extending from the fruit, with the cover positioned to cover the upper part of the fruit.

[0048] By positioning the cover to cover the top of the fruit, you can protect it from sunburn, rain, and pests that climb the branches.

[0049] (22) The bags of the present invention described above can be used in fruit tree cultivation methods. For example, a fruit tree cultivation method includes the step of fixing the opening of a bag to a branch extending from a fruit while the fruit is contained in any of the bags described in (15) to (20) above.

[0050] By placing the fruit in bags, it can be protected from sunburn, rain, and pests that crawl along the branches.

[0051] Figure 1 is a schematic perspective view showing an example of a sheet according to the embodiment. Figure 2 is a cross-sectional view taken along line II-II of Figure 1, showing an example where the contact angle of the substrate is large. Figure 3 is a cross-sectional view showing an example where the contact angle of the substrate is small. Figure 4 is a cross-sectional view showing another example of a sheet according to the embodiment. Figure 5 is a schematic perspective view showing an example of a cover according to the embodiment. Figure 6 is a schematic diagram showing the cover shown in Figure 5 in an unfolded state. Figure 7 is another example of a cover according to the embodiment, a schematic diagram showing the cover in an unfolded state. Figure 8 is a schematic diagram showing yet another example of a cover according to the embodiment. Figure 9 is a schematic diagram showing an example of a bag according to the embodiment. Figure 10 is a graph showing the results of the air permeability test in a test example.

[0052] Specific examples of the sheet, cover, bag, and fruit tree cultivation method using the cover or bag of the present invention will be described with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. In each drawing, some parts of the configuration may be exaggerated or simplified for ease of explanation. The dimensional ratios of parts in the drawings may also differ from those of the actual components. It should be noted that the present invention is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included. It should be understood that at least one configuration or feature described in each embodiment and example can be combined with other embodiments and examples, or modified in various ways.

[0053] [Embodiment] <Sheet> The sheet 1 of the embodiment will be described with reference to Figures 1 to 4. The sheet 1 shown in Figure 1 is a long material wound in a roll. The sheet 1 is pulled out from the roll when in use. The sheet 1 pulled out from the roll may be cut to a desired length. The sheet 1 is mainly used to protect fruit. The sheet 1 is used in the form of a cover 2 that covers fruit 7, for example, as will be described later with reference to Figure 5. The size of the sheet 1 may be a size that can cover fruit 7. The size of the sheet 1 will be described later. In this example, fruit 7 is grapes.

[0054] The sheet 1 of the embodiment comprises a base material 11 made of resin. The base material 11 has a plurality of ventilation holes 12 that penetrate through the front and back surfaces of the base material 11. One of the features of the sheet 1 of the embodiment is that the thickness t of the base material 11, the diameter d of each ventilation hole 12, and the pitch p between the centers of adjacent ventilation holes 12 satisfy a specific range.

[0055] <<Substrate>> The substrate 11 is the base of the sheet 1. The substrate 11 is formed of, for example, a thermoplastic resin. Examples of thermoplastic resins include acrylic resin, polyvinyl chloride resin, polyethylene terephthalate (PET) resin, polypropylene (PP) resin, polyethylene resin, polycarbonate resin, or polyester resin. The resins listed above have excellent processability and mass-producibility. Polyethylene terephthalate resin, polypropylene resin, and polyethylene resin do not absorb water even when used outdoors and are easy to use stably for long periods of time. Polyethylene terephthalate resin and polypropylene resin have high water resistance and high flexural strength. The substrate 11 may be formed of a single resin from among the resins listed above, or it may be formed of a resin composition in which multiple resins are combined. The substrate 11 may, for example, contain at least one of polyethylene terephthalate resin and polypropylene resin. A substrate 11 containing at least one of polyethylene terephthalate resin and polypropylene resin makes it easier for the shape of the sheet 1 to be maintained over a long period of time even when subjected to water pressure from wind and rain.

[0056] The base material 11 may optionally contain insect repellents, insecticides, anti-fogging agents, ultraviolet absorbers, infrared absorbers, antistatic agents, etc. A base material 11 containing at least one of an insect repellent and an insecticide is more effective at protecting fruits from pests. A base material 11 containing an anti-fogging agent is more effective at preventing dew and frost. A base material 11 containing an ultraviolet absorber is more effective at preventing sunburn on fruits. A base material 11 containing an infrared absorber has excellent heat shielding properties.

[0057] The substrate 11 may contain a filler that scatters sunlight. The surface of the substrate 11 may have fine irregularities. The surface of the substrate 11 is the surface that faces upward or outward when the sheet 1 is used in the form of the cover 2 shown in Figure 5 or the bag 3 shown in Figure 9. If the surface of the substrate 11 has fine irregularities, it will scatter sunlight more easily.

[0058] The base material 11 may have a single-layer structure as shown in Figures 2 and 3. The base material 11 may also have a multilayer structure as shown in Figure 4. In a multilayer base material 11, the contact angle differs between the center and the surface in the direction along the thickness t of the base material 11. The contact angle will be described later. The base material 11 shown in Figure 4 has a three-layer structure. The three-layer base material 11 comprises a first surface layer 111, an intermediate layer 113, and a second surface layer 112 in this order. The base material 11 may have multiple intermediate layers 113. In other words, the base material 11 may have a multilayer structure comprising four or more layers.

[0059] The multilayer substrate 11 may be formed by co-extruding multiple layers, or by laminating adjacent layers together with an adhesive. The first surface layer 111 and the second surface layer 112 may be formed by applying a surface treatment such as coating or plasma treatment to the surface of the intermediate layer 113. The multilayer substrate 11 makes it easier to maintain the shape of the sheet 1 over a long period of time even when subjected to water pressure from wind and rain.

[0060] The thickness t of the base material 11 is 20 μm or more and 300 μm or less. Thickness t is the distance between the front and back surfaces of the base material 11. If the base material 11 has a multilayer structure, thickness t is the total thickness of the multiple layers. If the thickness t is 20 μm or more, water will have difficulty passing from the front to the back surface of the base material 11. If the thickness t is 20 μm or more, the shape of the sheet 1 will be easier to maintain over a long period of time even when subjected to water pressure from wind and rain. For example, if the sheet 1 is used in the form of an umbrella-shaped cover 2 as shown in Figure 5 or a bag 3 as shown in Figure 9, the umbrella shape or bag shape will be easier to maintain over a long period of time even when subjected to water pressure from wind and rain. The thickness t may be greater than 20 μm, 25 μm or more, 30 μm or more, 45 μm or more, 70 μm or more, 90 μm or more, or 100 μm or more. If the thickness t is 300 μm or less, the sheet 1 will have excellent productivity and ease of installation, such as attaching the cover. The thickness t may be 250 μm or less, or 200 μm or less. The upper and lower limits of the thickness t can be any combination.

[0061] The contact angle θ of the substrate 11 is, for example, 65° or more or 40° or less. An example where the contact angle θ is 65° or more is shown in Figure 2, and an example where the contact angle θ is 40° or less is shown in Figure 3. The contact angle θ can be measured using a commercially available contact angle meter.

[0062] As shown in Figure 2, when the contact angle θ is 65° or greater, water does not easily wet the surface of the substrate 11. When the contact angle θ is 65° or greater, water does not easily pass through the ventilation holes 12 if the thickness t of the substrate 11, the diameter d of the ventilation holes 12 formed in the substrate 11, and the pitch p between the centers of adjacent ventilation holes 12 satisfy a specific range. The relationship between the contact angle θ, thickness t, diameter d, and pitch p will be described later. The contact angle θ may be 65° or greater or 70° or greater.

[0063] As shown in Figure 3, when the contact angle θ is 40° or less, water easily wets the surface of the substrate 11, and a water film is easily formed as the water spreads across the surface of the substrate 11. When the thickness t of the substrate 11 and the diameter d of the ventilation holes 12 formed in the substrate 11 meet a specific range, the water film has difficulty passing through the ventilation holes 12. The contact angle θ may also be 30° or less or 25° or less.

[0064] When the contact angle θ is moderate, exceeding 40° but less than 65°, the water leakage prevention characteristics are excellent if the thickness t of the base material 11 is sufficiently large and the diameter d of the ventilation holes 12 is sufficiently small. In this case, the thickness t of the base material 11 is, for example, 90 μm or more. The thickness t may also be 100 μm or more. The diameter d will be described later.

[0065] As shown in Figure 4, when the substrate 11 has a multilayer structure, the contact angles of the first surface layer 111 and the second surface layer 112 that form the front and back surfaces of the substrate 11 are, for example, less than 65°. The contact angle of the intermediate layer 113 is greater than the contact angles of the first surface layer 111 and the second surface layer 112. In other words, the contact angles of the first surface layer 111 and the second surface layer 112 are smaller than the contact angle of the intermediate layer 113. The contact angle of the intermediate layer 113 is, for example, 65° or more. The contact angles of the first surface layer 111 and the second surface layer 112 can be measured in the multilayer substrate 11. The contact angle of the intermediate layer 113 is considered to be the same as the contact angle of the resin layer, which has the same material and substantially the same surface properties as the intermediate layer 113 in the multilayer substrate 11. Here, "substantially the same surface properties" means that the arithmetic mean roughness Ra of the resin layer is within ±5% of the arithmetic mean roughness Ra of the first surface layer 111 or the second surface layer 112. The arithmetic surface roughness Ra is determined according to JIS B 0601:2013. When water comes into contact with the first surface layer 111, a film of water is formed around the periphery of the ventilation holes 12 formed in the first surface layer 111. If the contact angle of the intermediate layer 113 inside the ventilation holes 12 is greater than the contact angle of the first surface layer 111, water is less likely to pass through the ventilation holes 12 compared to the case where the contact angle of the intermediate layer 113 is equal to or less than the contact angle of the first surface layer 111. The same applies when water comes into contact with the second surface layer 112 as when water comes into contact with the first surface layer 111.

[0066] The contact angles of the first surface layer 111 and the second surface layer 112 may be 30° or less, or 25° or less. The contact angle of the intermediate layer 113 may be 70° or more. The difference between the contact angle of the first surface layer 111 and the contact angle of the intermediate layer 113, and the difference between the contact angle of the second surface layer 112 and the contact angle of the intermediate layer 113, is, for example, 15° or more. The above difference may be 30° or more, or 40° or more. If the above difference is large, water will have difficulty passing through the ventilation holes 12.

[0067] The Gurley stiffness of the base material 11 is, for example, 0.5 N or higher. When the Gurley stiffness is 0.5 N or higher, if the sheet 1 is used in the form of an umbrella-shaped cover 2 as shown in Figure 5, it is easier to maintain the umbrella shape over a long period of time even when subjected to water pressure from wind and rain. The Gurley stiffness of the base material 11 may be 0.7 N or higher or 1.2 N or higher. The Gurley stiffness of the base material 11 may be 0.2 N or lower. When the Gurley stiffness is 0.2 N or lower, if the sheet 1 is used in the form of a bag 3 as shown in Figure 9, the processability and workability of the bag 3 are excellent. The Gurley stiffness of the base material 11 may be 0.1 N or lower. The Gurley stiffness of the base material 11 is measured by the method described in JIS L 1085:1998.

[0068] The whiteness of the substrate 11 is, for example, 50% or more, 80% or more, or 90% or more. The whiteness of the substrate 11 is measured by the method described in JIS L 1015:2010.

[0069] The opacity of the substrate 11 is, for example, 40% or more, 80% or more, or 95% or more. The opacity of the substrate 11 is measured by the method described in JIS P 8149:2000.

[0070] The haze value of the substrate 11 is, for example, 40% or more, 60% or more, or 80% or more. The haze value of the substrate 11 is measured by the method described in JIS K 7136:2000.

[0071] The glossiness of the substrate 11 is, for example, 5% or more. The glossiness of the substrate 11 is measured by the method described in JIS P 8142:2005.

[0072] The total light reflectance of the substrate 11 is, for example, 50% or more, 70% or more, or 80% or more. The total light reflectance of the substrate 11 is measured by the method described in JIS K 7375:2008.

[0073] The heat shielding rate of the base material 11 is, for example, 20% or more, 70% or more, or 75% or more. The heat shielding rate of the base material 11 is measured by the method described in JIS L 1951:2019.

[0074] When the fruit is covered with the base material 11 in which at least one of the whiteness, opacity, haze value, glossiness, total light reflectance, and heat insulation rate of the base material 11 satisfies the above-described range, it is easy to prevent the temperature rise of the fruit, and it has effects such as creating an appropriate shade for the fruit and preferably scattering sunlight so that it is easy to irradiate the entire fruit with light. In addition to heat insulation properties, the base material 11 is also required to have light shielding properties. When the fruit is covered with the base material 11 having excellent light shielding properties, it is difficult for direct sunlight to directly hit the fruit. In addition, it is expected that the fruit covered with such a base material 11 will be uniformly irradiated with light weakened to a certain extent compared to direct sunlight. When the fruit is covered with the base material 11 having excellent heat insulation and light shielding properties, it is possible to prevent sunburn, cracking, etc. of the fruit and grow fruits excellent in shape and color and taste.

[0075] The air permeability of the base material 11 is, for example, 1000 seconds or less. The air permeability of the base material 11 is the time for a predetermined amount of air (100 cc, 1.29 kPa) to pass through the base material 11 under a predetermined pressure. The air permeability of the base material 11 is measured by the method described in JIS P 8117:2009. The base material 11 with an air permeability of 1000 seconds or less has excellent air permeability. If the base material 11 has an air permeability of 1000 seconds or less, heat and moisture are less likely to accumulate, and the occurrence of mold or diseases can be prevented. When the sheet 1 is used in the form of the umbrella-shaped cover 2 shown in FIG. 5, the air permeability in the vertical direction is ensured, and dew condensation is unlikely to occur. The air permeability of the base material 11 may be 100 seconds or less, 20 seconds or less, or 10 seconds or less.

[0076] The water absorption (Cobb) of the base material 11 is, for example, 0.5 g / m ２ or less. The water absorption of the base material 11 is measured by the method described in JIS P 8140:1998. The base material 11 with a water absorption of 0.5 g / m ２ or less has excellent water leakage prevention characteristics and is hardly affected by precipitation or pesticide spraying. The water absorption of the base material 11 may be 0.3 g / m ２ or less, or 0.2 g / m ２ or less.

[0077] The shape of the base material 11 can be appropriately selected depending on how the sheet 1 is used. The shape of the base material 11 may be a long, rectangular shape as shown in Figure 1, or a rectangular shape (Figure 6) that can form an umbrella shape as shown in Figure 5. The shape of the base material 11 may be a square or a rectangle. The shape of the base material 11 may be a polygon other than a rectangle. The shape of the base material 11 may be a circle. The shape of the base material 11 may be an irregular shape defined by a closed curve, and the sheet 1 can be cut into the desired shape.

[0078] When protecting grapes with a rectangular sheet 1, the length of one side of the base material 11 is, for example, 200 mm to 500 mm, or 250 mm to 400 mm. A base material 11 of this size can protect the entire bunch of grapes while minimizing the disruption to the growth of other adjacent bunches. In the case of a rectangular sheet 1, the aspect ratio of the base material 11 can be appropriately changed from 2:3 to 9:10. The size of the base material 11 can be appropriately selected to cover fruits such as grapes.

[0079] <Ventilation Holes> The ventilation holes 12 are provided to prevent moisture from accumulating near the fruit when the fruit is covered with the base material 11, and to supply and release oxygen and carbon dioxide. In the sheet 1 shown in Figure 1, multiple ventilation holes 12 are provided at equal intervals across the entire surface of the base material 11. In this example, the opening shape of each ventilation hole 12 is circular.

[0080] The opening shape of the ventilation hole 12 may be a perfect circle, an ellipse, a square, a rectangle, or a polygon. The opening shape of the ventilation hole 12 may also be a shape in which multiple holes overlap. Multiple ventilation holes 12 may all have the same opening shape, or they may all have different opening shapes.

[0081] The diameter d of each ventilation hole 12 is 0.10 mm or more and 0.50 mm or less. The diameter d is the equivalent diameter of a circle, and is the diameter of a perfect circle with the same size as the opening area of ​​the ventilation hole 12. If the diameter d is 0.10 mm or more, ventilation is easily improved. The diameter d may also be 0.15 mm or more or 0.18 mm or more. If the diameter d is 0.50 mm or less, waterproofing is easily improved. The diameter d may also be less than 0.50 mm, 0.40 mm or less, 0.30 mm or less, 0.25 mm or less, 0.22 mm or less, or 0.20 mm or less. The upper and lower limits of the diameter d can be combined arbitrarily. Multiple ventilation holes 12 may all have the same diameter d, or they may have different diameters d.

[0082] The pitch p between the centers of adjacent ventilation holes 12 is 5 mm or more and 30 mm or less. The center of a ventilation hole 12 is the centroid of the area of ​​the ventilation hole 12. For example, if the opening shape of the ventilation hole 12 is a perfect circle, the center of that circle is the center of the ventilation hole 12. If the opening shape of the ventilation hole 12 is a square or rectangular shape, the intersection of the diagonals of each shape is the center of the ventilation hole 12. A pitch p of 5 mm or more tends to improve waterproofing. The pitch p may also be 7 mm or more, or 8 mm or more. A pitch p of 30 mm or less tends to improve ventilation. The pitch p may also be 25 mm or less, 20 mm or less, 15 mm or less, or 12 mm or less. The upper and lower limits of the pitch p can be combined arbitrarily.

[0083] Depending on how the sheet 1 is used, the pitch p may differ in different locations. For example, in the case of the elongated base material 11 shown in Figure 1, the pitch p may increase from near the center in the width direction of the base material 11 outwards. In the case of the rectangular base material 11 shown in Figure 6, the pitch p may increase radially from near the center of the base material 11 outwards. Ventilation holes 12 may not be provided in some parts of the base material 11. It is preferable to provide many ventilation holes 12 in places where moisture tends to accumulate when the fruit is covered with the base material 11.

[0084] Referring to Figures 2 to 4, the relationship between the thickness t of the base material 11, the contact angle θ, the diameter d of the ventilation holes 12, and the pitch p will be explained below. The ventilation holes 12 penetrate the base material 11 in a columnar shape. The thickness t of the base material 11 corresponds to the depth of the ventilation holes 12. The size of a raindrop 9 that falls freely in the air is usually 0.5 mm to 0.8 mm. If the diameter d of the ventilation holes 12 is smaller than the size of the raindrop 9, the raindrop 9 will have difficulty penetrating the ventilation holes 12 while maintaining its free-fall shape. Even when raindrops 9 fall while the surface of the base material 11 is wet, if the thickness t, diameter d, and pitch p satisfy the above-mentioned range, the resistance that water experiences when passing through the ventilation holes 12 will increase, and the speed of water passing through the ventilation holes 12 will decrease. Therefore, even when it rains heavily, the speed of water passing through the ventilation holes 12 is reduced, and water passing through the ventilation holes 12 and falling onto the fruit is prevented. Note that either the front or back surface of the base material 11 may be the surface that gets wet. When the sheet 1 is used in the form of the umbrella-shaped cover 2 shown in Figure 5 or the bag 3 shown in Figure 9, either the front or back surface of the base material 11 may face outwards.

[0085] As shown in Figure 2, when the contact angle θ is 65° or greater, water does not easily wet the surface of the substrate 11. When the contact angle θ is 65° or greater, for example, the thickness t is 90 μm or more and 300 μm or less, the diameter d is 0.18 mm or more and 0.22 mm or less, and the pitch p is 5 mm or more and 30 mm or less. When the contact angle θ is 65° or greater, the pitch p may be 8 mm or more.

[0086] As shown in Figure 3, when the contact angle θ is 40° or less, water easily wets the surface of the substrate 11, and a water film is easily formed as the water spreads across the surface of the substrate 11. When the contact angle θ is 40° or less, for example, the thickness t is 90 μm or more and 300 μm or less, the diameter d is 0.18 mm or more and 0.22 mm or less, and the pitch p is 5 mm or more and 30 mm or less. When the contact angle θ is 40° or less, the thickness t may be 95 μm or more. When the contact angle θ is 40° or less, the pitch p may be 15 mm or more.

[0087] As shown in Figure 4, when the substrate 11 has a multilayer structure, the contact angles of the first surface layer 111 and the second surface layer 112 forming the front and back surfaces of the substrate 11 are less than 65°, and the contact angle of the intermediate layer 113 is greater than the contact angles of the first surface layer 111 and the second surface layer 112. In this case, the thickness t is, for example, 90 μm or more, 100 μm or more, or 130 μm or more. Alternatively, the thickness t is, for example, 300 μm or less, 270 μm or less, or 250 μm or less. The diameter d is, for example, 0.30 mm or less, 0.25 mm or less, or 0.22 mm or less. The pitch p is, for example, 5 mm or more, or 8 mm or more.

[0088] Multiple ventilation holes 12 can be formed on the substrate 11 by using laser processing, die punching, or thermal needle processing. Laser processing allows for fine and high-precision hole drilling.

[0089] The area ratio of the multiple ventilation holes 12 is, for example, 0.005% or more and 0.50% or less. The area ratio of the multiple ventilation holes 12 is the ratio of the total area of ​​the multiple ventilation holes 12 to a predetermined area of ​​the base material 11. The predetermined area of ​​the base material 11 is, for example, 10 cm x 10 cm. The area ratio of the multiple ventilation holes 12 may also be 0.02% or more and 0.20% or less. If the area ratio of the multiple ventilation holes 12 is within the above range, it is easy to achieve both sufficient ventilation and water leakage prevention characteristics. The area ratio of the multiple ventilation holes 12 may also be 0.03% or more, or 0.10% or more.

[0090] Sheet 1 is used in the form of an umbrella-shaped cover 2 as shown in Figure 5, or in the form of a bag 3 as shown in Figure 9.

[0091] <Cover> The cover 2 shown in Figure 5 is formed from a resin base material 21. The base material 21 has a size corresponding to the size of the object to be covered. The object to be covered is a fruit 7. The base material 21 has the same configuration as the base material 11 of the sheet 1 described above. The base material 21 has a plurality of ventilation holes 22 and notches 23. Each ventilation hole 22 penetrates through the front and back of the base material 21. The ventilation holes 22 have the same configuration as the ventilation holes 12 of the base material 11 described above. The notches 23 are provided from the periphery of the base material 21 toward the center. The center does not have to be the center point of the base material 21, but may be within a region that extends from the periphery of the base material 21 toward approximately the center point. The cover 2 is formed in an umbrella shape by overlapping base material 21 of a size corresponding to the size of the fruit 7 at the notch 23 portion.

[0092] The shape of the base material 21 is, for example, a rectangular shape as shown in Figure 6. In this example, the rectangular shape is a square. The notch 23 is made from one of the four sides of the base material 21 toward the center of the base material 21. In this example, one notch 23 is made to form an umbrella shape. The end portion 24 of the notch 23 passes through the axis of the umbrella shape. As shown in Figure 5, a branch 8 extending from the fruit 7 is placed at the end portion 24. In other words, the base material 21 formed in the shape of an umbrella has a generally conical surface. The part corresponding to the apex of the conical surface is attached to the branch 8 facing upward. The end portion 24 may have a hole through which the branch 8 is inserted. The length L along the notch 23 is, for example, 1 / 10 to 1 / 5 of the circumference of the base material 21. If the shape of the base material 21 is a square as in this example, the length L of the notch 23 is, for example, 2 / 5 to 3 / 5 of the length of one side of the square. In this example, the end portion 24 is located at the center point of the base material 21. In this example, the length L of the notch 23 is 1 / 2 the length of one side of the square and 1 / 8 the perimeter of the base material 21.

[0093] The notch 23 may be a V-shaped notch, as shown in Figure 7. The shape of the notch may also be rectangular, U-shaped, or fan-shaped.

[0094] The cover 2 has an umbrella shape formed by overlapping the peripheral portions of the notches 23. The overlapping portions around the notches 23 are fixed by fixing parts 25, as shown in Figure 5. The fixing parts 25 can be formed, for example, by a stapler or adhesive. In this example, the fixing part 25 is a staple. Although only one staple is shown in Figure 5, multiple fixing parts 25 may be formed by multiple staples along the overlapping peripheral portions of the notches 23. The adhesive is applied, for example, to the area around the notches 23 of the base material 21 to form an adhesive layer. Before forming the umbrella shape, a release layer is attached to the surface of the adhesive layer. When forming the umbrella shape, the release layer is peeled off and the peripheral portions of the notches 23 are overlapped.

[0095] The umbrella-shaped base material 21 has a larger surface area than the fruit 7 when viewed along the axis of the umbrella shape. The surface area of ​​the fruit 7 is the surface area when the fruit 7 is covered by the cover 2 and viewed along the axis of the umbrella shape. Because the surface area of ​​the umbrella-shaped base material 21 is larger than the surface area of ​​the fruit 7, the fruit 7 can be protected from sunburn, rain, and pests that travel along the branches.

[0096] The fruit tree cultivation method using cover 2 includes the step of fixing cover 2 to a branch 8 extending from fruit 7 while cover 2 is positioned to cover the top of fruit 7. Specifically, the notch 23 of the base material 21 is opened and the branch 8 is inserted through the end portion 24 of the notch 23. Subsequently, the surrounding portions of the notch 23 are overlapped and the umbrella shape is maintained with the fixing portion 25. The notch 23 makes it easy to create an umbrella-shaped cover 2 on top of fruit 7.

[0097] The fixing portion 25 is not particularly limited as long as it is a means that can maintain the umbrella shape formed by overlapping the peripheral portions of the notches 23. For example, as shown in Figure 8, a tongue piece 26 and a mounting hole 27 can be formed in the base material 21, and the umbrella shape can be formed by inserting the tongue piece 26 into the mounting hole 27. In Figure 8, for the sake of explanation, the ventilation hole 22 is not shown. In the upper part of Figure 8, two notches 261 and 262 are formed in the corner of the base material 21. The two notches 261 and 262 make the corner of the base material 21 bendable relative to the base material 21. This bendable portion is the tongue piece 26. The mounting hole 27 penetrates both the front and back of the base material 21 so that the tongue piece 26 can be inserted. The distance between the starting ends of the notches 261 and 262 is wider than the distance between the ending ends of the notches 261 and 262. Of the ends of the notches 261 and 262, the starting end is the end that overlaps with the periphery of the base material 21, and the ending end is the end that is located away from the periphery of the base material 21. Such a tongue piece 26 has a shape in which the width widens once from the bend connecting the ending ends toward the corner and then narrows again. Therefore, the tongue piece 26 inserted into the mounting hole 27 is difficult to remove. This mounting hole 27 is provided near the corners adjacent to the corners of the tongue piece 26, with the notch 23 in between. The mounting hole 27 shown in this example is a flattened triangular shape. The notch 23 is formed between the tongue piece 26 and the mounting hole 27. In the configuration shown in Figure 8, as shown in the lower part of Figure 8, the umbrella shape can be maintained by inserting the branch 8 through the ending end 24 of the notch 23, overlapping the peripheral parts of the notch 23, and inserting the tongue piece 26 into the mounting hole 27.

[0098] Although not shown in the diagram, the cover 2 may be fixed to the branch 8 by tightening the end portion 24 using the uneven surface of the branch 8. Alternatively, the cover 2 may be fixed to the branch 8 using clips or the like.

[0099] By positioning cover 2 to cover the top of the fruit 7, the fruit 7 can be protected from sunburn, rain, and pests that climb the branches 8.

[0100] <Bag> The bag 3 shown in Figure 9 is formed from a base material 31 made of resin. The base material 31 has a size corresponding to the size of the fruit 7. The base material 31 has the same structure as the base material 11 of the sheet 1 described above. The base material 31 has a plurality of ventilation holes 32. Each ventilation hole 32 penetrates through the front and back of the base material 31. The ventilation holes 32 have the same structure as the ventilation holes 12 of the base material 11 described above. The bag 3 is formed in the shape of a bag from a base material 31 that is sized according to the size of the fruit 7.

[0101] Bag 3 may be formed, for example, by overlapping two rectangular base materials 31 and fusing the three sides around the perimeter, leaving the remaining side open, forming a three-sided bag shape. Bag 3 may also be formed by folding one rectangular base material 31 so that the top side is open, the bottom side is folded, and the two side sides are joined. Bag 3 may also be formed by folding one rectangular base material 31, fusing the back surfaces of the ends together, and fusing one opening of the resulting cylindrical base material 31 to form a gusseted bag shape. The shape of bag 3 can be appropriately selected according to the type, size, and use of the fruit 7, such as a rectangular prism or a triangular pyramid.

[0102] In the bag 3 shown in Figure 9, the diameter and pitch of the ventilation holes 32 located at the top of the fruit 7 are relatively large, while the diameter and pitch of the ventilation holes 32 located at the bottom of the fruit 7 are relatively small. For the ventilation holes 32 located at the bottom of the fruit 7, the diameter of the ventilation holes 32 may be made larger and the pitch smaller to prioritize air permeability. For example, the pitch of the ventilation holes 32 located at the bottom of the fruit 7 may be about half the pitch of the ventilation holes 32 located at the top of the fruit 7.

[0103] The fruit tree cultivation method using bag 3 includes the step of fixing the opening of bag 3 to a branch 8 extending from the fruit 7 while the fruit 7 is contained in bag 3. A fastener or the like can be used to fix the opening of bag 3 to the branch 8. By containing the fruit 7 in bag 3, the fruit 7 can be protected from sunburn, rain, and pests that climb the branch 8.

[0104] [Test Example] In the test example, a sheet was prepared by forming multiple ventilation holes in a resin substrate, and the air permeability and waterproofing properties were investigated when the thickness of the substrate, the diameter of the ventilation holes, and the pitch between the centers of adjacent ventilation holes were varied.

[0105] <Sample> <Sample No. 1> The substrate is an unoriented PET film (FE2001, manufactured by Futamura Chemical Co., Ltd.). The substrate has a single-layer structure. The thickness of the substrate is 38 μm. The size of the substrate is 10 cm x 10 cm. CO ２ Multiple ventilation holes were formed on the entire surface of the substrate using a laser processing machine. The opening shape of the ventilation holes is circular. The diameter of the ventilation holes is 0.2 mm. The pitch of the ventilation holes is 10 mm. The diameter, pitch, and area ratio of the ventilation holes are shown in Table 1. The area ratio is the ratio of the total area of ​​the multiple ventilation holes to the base area of ​​the substrate, which is 10 cm x 10 cm. In Table 1, the material of the substrate is indicated as "PET". The contact angle of the substrate surface is 74.4°. The contact angle was measured using PG-X plus (Matsubo Co., Ltd. portable contact angle meter).

[0106] <<Sample No. 2 to Sample No. 4>> Using the same PET film as Sample No. 1, the diameter, pitch, and area ratio of the ventilation holes were formed as shown in Table 1.

[0107] <<Samples No. 5 to No. 8>> Using the same PET film as Sample No. 1, the substrate thickness was set to 50 μm, and the diameter, pitch, and area ratio of the ventilation holes were formed as shown in Table 1. In Table 1, the material of the substrate is indicated as "PET". The contact angle of the substrate surface is 71.5°.

[0108] ≪Sample No. 9 to Sample No. 12≫ The substrate is a polypropylene film (FPG150 manufactured by Yupo Corporation). This polypropylene film has a three-layer structure of [longitudinal porous stretched PP / unstretched PP / transverse porous stretched PP]. The contact angle of the porous stretched PP, which corresponds to the first and second surface layers forming the front and back surfaces of the substrate, is 61.0°. The contact angle of the unstretched PP, which corresponds to the intermediate layer, is 76°. The thickness of the substrate, i.e., the total thickness of the three layers, is 150 μm. Multiple ventilation holes were formed in this substrate with the diameter, pitch, and area ratio shown in Table 1. In Table 1, the material of the substrate is indicated as "synthetic PP". Note that in these samples and in the samples described later where the substrate has a three-layer structure, the contact angles shown in Table 2 are the contact angles of the first and second surface layers.

[0109] <<Samples No. 13 to No. 16>> Using the same polypropylene film as Sample No. 9, the substrate thickness was set to 80 μm, and the diameter, pitch, and area ratio of the ventilation holes were formed as shown in Table 1. In Table 1, the material of the substrate is indicated as "synthetic PP". The contact angle between the first and second surface layers of the substrate is 57.9°. The contact angle between the first and second surface layers is smaller than the contact angle of the intermediate layer.

[0110] ≪Sample No. 17 to Sample No. 20≫ The substrate is a biaxially oriented polypropylene film (Toyobo P2161). This biaxially oriented polypropylene film has a three-layer structure with a corona-treated surface. The contact angle of the first and second surface layers that form the front and back surfaces of the substrate is 22.6°. The surface of this substrate has a smaller contact angle than the surface of a normal polypropylene film. The contact angle of a normal polypropylene film is about 70° to 90°. The contact angle of the intermediate layer is 70° to 90°. The thickness of the substrate is 40 μm. Multiple ventilation holes were formed in this substrate with the diameter, pitch, and area ratio shown in Table 1. In Table 1, the material of the substrate is indicated as "OPP".

[0111] <<Sample No. 21 to Sample No. 24>> Using the same biaxially oriented polypropylene film as Sample No. 17, the substrate thickness was set to 20 μm, and the diameter, pitch, and area ratio of the ventilation holes were formed as shown in Table 1. In Table 1, the material of the substrate is indicated as "OPP". The contact angle between the first and second surface layers of the substrate is 21.5°. The contact angle between the first and second surface layers is smaller than the contact angle of the intermediate layer.

[0112] <<Samples No. 25 to No. 28>> The substrate is a hologram film, the same as in Sample No. 9, with a hologram sheet bonded to the surface of the polypropylene film. The thickness of the polypropylene film is 83 μm. The thickness of the hologram sheet is 23 μm. The thickness of the substrate is 106 μm. The diameter, pitch, and area ratio of the ventilation holes were formed as shown in Table 1. In Table 1, the material of the substrate is indicated as "hologram".

[0113] ≪Sample No. 101≫ The substrate is milky white polyethylene. The thickness of the substrate is 121 μm. No ventilation holes are formed in the substrate. In Table 1, the material of the substrate is indicated as "milky white poly".

[0114] <<Sample No. 102>> The base material is kraft paper. The thickness of the base material is 157 μm. No ventilation holes are formed in the base material.

[0115] ≪Sample No. 103≫ The base material is wax-coated kraft paper on both sides. The thickness of the base material is 566 μm. No ventilation holes are formed in the base material. In Table 1, the material of the base material is indicated as "wax-coated paper".

[0116] <<Sample No. 104>> In the same PET film as Sample No. 1, the diameter, pitch, area ratio, and pitch of the ventilation holes were formed as shown in Table 1. The thickness of the substrate is 38 μm. In Table 1, the material of the substrate is indicated as "PET".

[0117]

[0118] <Water Leakage Test> A shaking water leakage test was performed using a Gurley-type Cobb size measuring instrument. The test was performed in accordance with the Cobb method described in JIS P 8140:1998. The sheet was sandwiched horizontally between the packings of a pair of flasks, and 58.06 ml of water was placed in the flask above the sheet and the stopper was applied. The entire flask was then vibrated 10 times with an amplitude of 200 mm and a period of 2 cycles / second to cause water to collide with it, and it was checked whether or not water droplets leaked onto the back of the sheet. This is labeled as "Shaking" in Table 2. In addition, as a time-dependent water leakage test, water was dropped onto the top surface of the sheet and left to stand for 10 minutes, and it was checked whether or not water droplets leaked onto the back of the sheet. This is labeled as "Standing" in Table 2. The water leakage prevention characteristics were evaluated based on the above two water leakage tests. The results are shown in Table 2. In Table 2, in both tests, samples with no leakage are indicated as OK, and samples with leakage are indicated as NG. In the time-dependent water leakage test, samples No. 1 to No. In all 28 cases, it was confirmed that no water leakage occurred.

[0119] <Water Absorption Test> A water absorption test was conducted using a Gurley-type Cobb size measuring instrument. The test was performed in accordance with the Cobb method described in JIS P 8140:1998. The results are shown in Table 2. Samples No. 102 and No. 103 were confirmed to have very high water absorption.

[0120] <Air Permeability Test> The air permeability of the sheet was measured using an air permeability tester (Gurley type densometer G-B3C, Toyo Seiki Seisakusho Co., Ltd.). The measured air volume was 100 cc, and the density was 860 ± 30 kg / m³. ３ The test was conducted using 100 cc of oil (sealed fluid) with a viscosity at 20°C within the range of 16 cP to 19 cP as specified in ISO 3104, and a flash point of 135°C or higher. The results are shown in Table 2 and Figure 10. In Figure 10, the vertical axis represents air permeability, and the horizontal axis represents the area ratio of the vents. The unit of air permeability is seconds, and the unit of the area ratio of the vents is %. A smaller value for air permeability indicates that the time required for the measured air to pass through the sample is shorter, resulting in better air permeability. As shown in Figure 10, it can be confirmed that as the area ratio of the vents increases, the value of air permeability decreases, and air permeability improves. In particular, when the area ratio of the vents is 0.01% or less, the air permeability increases sharply, when the area ratio of the vents is 0.02% or more, there is sufficient air permeability, and when it is 0.04% or more, there is almost no air permeability resistance. Furthermore, it was confirmed that this ventilation tendency does not depend on the material or thickness of the substrate, nor does it depend solely on either the diameter or pitch of the ventilation holes. Samples No. 101 and No. 103 were found to have extremely poor ventilation. The ventilation of samples No. 101 and No. 103 was determined to be 10, which is the measurement limit of this testing machine, based on the ventilation conditions. ６ Since it was expected to take longer than a second, measurement was deemed impossible.

[0121] <Heat Shielding Test> A sheet was placed 30.0 cm away from an infrared heater (TEKNOS Parabolic Halogen Heater Floor Standing PH800, manufactured by Senju Co., Ltd.) so that the light shone perpendicularly on the sheet. A thermometer was placed another 30.0 cm away from the sheet, and the temperature of the thermometer was measured after 10 minutes with the infrared heater set to 800W. The percentage increase in temperature with and without the sheet was then calculated. In Table 2, this is labeled as "Heat Shielding Performance". The results are shown in Table 2. It was confirmed that the 150 μm polypropylene film and the hologram film exhibited excellent heat shielding properties.

[0122] <Gurley Stiffness Test> The stiffness (bending resistance) of the sheet was measured using a Gurley stiffness tester (Toyo Seiki Manufacturing Co., Ltd. Digital Gurley Flexibility Tester GS-3). In Table 2, it is referred to as "Gurley". The results are shown in Table 2. It was confirmed that particularly high bending resistance was obtained when the thickness of the base material was 100 μm or more.

[0123]

[0124] From the results in Table 2, samples No. 1 to No. 28 showed no leakage in the static leakage test and had an air permeability of 70 seconds or less, confirming their excellent water leakage prevention characteristics and air permeability. In sample No. 104, leakage occurred from the substrate due to the large diameter of the ventilation holes.

[0125] As seen in samples No. 1 to No. 8, when the contact angle is large (65° or more), reducing the diameter of the ventilation holes prevented leakage even in the shaking leakage test, confirming that leakage can be prevented even under water pressure. As seen in samples No. 17 to No. 24, when the contact angle of the substrate surface is small (40° or less), reducing the diameter of the ventilation holes also made it easier to waterproof against water pressure. In particular, it was confirmed that leakage could be prevented when the substrate thickness was greater than 20 μm. This immersion leakage test simulates wind and rain. These samples, which can prevent leakage in the immersion leakage test, are considered to have excellent water leakage characteristics even when used in environments where they may be exposed to wind and rain.

[0126] In samples No. 13 to No. 16, which had a contact angle of 57.9°, leakage occurred in the shaking leakage test. Excluding samples No. 13 to No. 16 and sample No. 21, it was confirmed that the water leakage prevention characteristics could be maintained by reducing the diameter of the vent holes. Comparing samples No. 13 to No. 16 with samples No. 9 to No. 12, it was confirmed that even in the case of moderate contact angles between 40° and 65°, such as sample No. 9 and No. 11, water leakage could be prevented by increasing the thickness of the substrate and reducing the diameter of the vent holes. These samples, which can prevent water leakage in the immersion leakage test, are considered to have excellent water leakage prevention characteristics even when used in environments where they may be exposed to wind and rain.

[0127] Comparing sample No. 21 and sample No. 23, the shaking leak test results confirmed that even under the same conditions, a larger vent pitch can prevent water leakage. Comparing sample No. 17 and sample No. 21, the shaking leak test results confirmed that a thicker substrate can prevent water leakage. Based on the above, the following was confirmed: Water leakage when water pressure is present is less likely to occur when the contact angle is large (60° or more) or small (less than 40°). Water leakage is less likely to occur when the diameter of the vent holes is small. Water leakage is less likely to occur when the substrate is thicker. Water leakage is less likely to occur when the vent pitch is large. Water leakage is less likely to occur when the contact angle is medium. Water leakage is less likely to occur when the substrate is thicker and the diameter of the vent holes is small. Water leakage is less likely to occur when the pitch is small and the diameter of the vent holes is large in order to ensure air permeability.

[0128] In all samples from No. 1 to No. 28, it was confirmed that the air permeability was low and that there was sufficient breathability. In particular, when the area ratio of the ventilation holes was 0.02% or more, the air permeability was 20 seconds or less, confirming extremely excellent breathability.

[0129] For samples No. 9 to No. 12 and No. 25 to No. 28, which have a substrate thickness of 100 μm or more, it was confirmed that the Gurley stiffness was 0.5 N or higher. Since samples No. 9 to No. 12 also had low water absorption, it is thought that samples No. 25 to No. 28 would also likely have low water absorption. It is thought that samples No. 9 to No. 12 and No. 25 to No. 28 can maintain their umbrella or bag shape even when exposed to wind and rain for a long period of time, preventing problems caused by contact with fruit.

[0130] It was confirmed that the heat-shielding properties improve depending on the thickness of the substrate.

[0131] 1 Sheet 11 Base material 111 First surface layer, 112 Second surface layer, 113 Intermediate layer 12 Ventilation holes t Thickness d Diameter p Pitch θ Contact angle 2 Cover 21 Base material 22 Ventilation holes 23 Notch 24 End part 25 Fixing part 26 Tongue piece 261, 261 Notch 27 Mounting hole 3 Bag 31 Base material 32 Ventilation holes 7 Fruit 8 Branch 9 Raindrop

Claims

1. A sheet comprising a resin substrate, wherein the thickness of the substrate is 20 μm or more and 300 μm or less, the substrate has a plurality of ventilation holes penetrating both the front and back surfaces of the substrate, the equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less, and the pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less.

2. The sheet according to claim 1, wherein the contact angle of the substrate is 65° or more or 40° or less, and the equivalent circular diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.22 mm or less.

3. The sheet according to claim 1, wherein the thickness of the substrate is 90 μm or more, the contact angle of the substrate is greater than 40° and less than or equal to 65°, and the equivalent circular diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.22 mm or less.

4. The sheet according to claim 1, wherein the substrate comprises a first surface layer, an intermediate layer, and a second surface layer in that order, the thickness of the substrate is 90 μm or more, the equivalent diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less, the pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less, and the contact angle of each of the first surface layer and the second surface layer is smaller than the contact angle of the intermediate layer.

5. The sheet according to any one of claims 1 to 4, wherein the substrate comprises at least one of polyethylene terephthalate resin and polypropylene resin.

6. The sheet according to any one of claims 1 to 5, wherein the ratio of the total area of ​​the plurality of ventilation holes to a predetermined area of ​​the base material is 0.02% or more and 0.20% or less.

7. The sheet according to any one of claims 1 to 6, wherein the heat shielding rate of the base material is 70% or more.

8. A cover formed of a resin substrate, wherein the thickness of the substrate is 20 μm or more and 300 μm or less, the substrate has a plurality of ventilation holes and notches, the plurality of ventilation holes penetrate through the front and back surfaces of the substrate, the equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less, the pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less, the notches are provided from the periphery of the substrate toward the center, and the umbrella shape is formed by overlapping the peripheral portions of the notches, and the umbrella-shaped substrate has a larger area than the object to be covered when viewed in the direction along the axis of the umbrella shape.

9. The cover according to claim 8, wherein the contact angle of the outward-facing surface of the substrate is 65° or more or 40° or less, and the equivalent circular diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.22 mm or less.

10. The cover according to claim 8, wherein the thickness of the substrate is 90 μm or more, the contact angle of the outward-facing surface of the substrate is greater than 40° and less than or equal to 65°, and the equivalent circular diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.22 mm or less.

11. The cover according to claim 8, wherein the substrate comprises a first surface layer, an intermediate layer, and a second surface layer in that order, the thickness of the substrate is 90 μm or more, the equivalent diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less, the pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less, and the contact angle of each of the first surface layer and the second surface layer is smaller than the contact angle of the intermediate layer.

12. The cover according to any one of claims 8 to 11, wherein the substrate comprises at least one of polyethylene terephthalate resin and polypropylene resin.

13. The cover according to any one of claims 8 to 12, wherein the ratio of the total area of ​​the plurality of ventilation holes to a predetermined area of ​​the base material is 0.02% or more and 0.20% or less.

14. The cover according to any one of claims 8 to 13, wherein the heat shielding rate of the base material is 70% or more.

15. A bag formed of a resin substrate, wherein the thickness of the substrate is 20 μm or more and 300 μm or less, the substrate has a plurality of ventilation holes penetrating both the front and back surfaces of the substrate, the equivalent diameter of each of the plurality of ventilation holes is 0.10 mm or more and 0.50 mm or less, and the pitch between the centers of adjacent ventilation holes is 5 mm or more and 30 mm or less.

16. The bag according to claim 15, wherein the contact angle of the outward-facing surface of the substrate is 65° or more or 40° or less, and the equivalent circular diameter of each of the plurality of ventilation holes is 0.18 mm or more or 0.22 mm or less.

17. The bag according to claim 15, wherein the substrate comprises a first surface layer, an intermediate layer, and a second surface layer in that order, the thickness of the substrate is 90 μm or more, the equivalent diameter of each of the plurality of ventilation holes is 0.18 mm or more and 0.30 mm or less, the pitch between the centers of adjacent ventilation holes is 5 mm or more and 12 mm or less, and the contact angle of each of the first surface layer and the second surface layer is smaller than the contact angle of the intermediate layer.

18. The bag according to any one of claims 15 to 17, wherein the base material comprises at least one of polyethylene terephthalate resin and polypropylene resin.

19. The bag according to any one of claims 15 to 18, wherein the ratio of the total area of ​​the plurality of ventilation holes to a predetermined area of ​​the base material is 0.02% or more and 0.20% or less.

20. The bag according to any one of claims 15 to 19, wherein the heat shielding rate of the base material is 70% or more.

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