Agricultural greenhouse curtain material

Abstract

To provide an agricultural greenhouse curtain material that can satisfy light transmissivity and heat shielding property more securely than conventional products.SOLUTION: An agricultural greenhouse curtain material in which acrylic hollow particles or glass-based hollow particles are held in a dispersion state on both surfaces and inside a polyester-based continuous fiber nonwoven fabric. Preferably, the acrylic hollow particles or glass-based hollow particles are held by polyester-based continuous fiber nonwoven fabric by a binder. More preferably, a cross-sectional shape of the polyester-based continuous fiber constituting the polyester-based continuous fiber nonwoven fabric is flat, major axis / minor axis being a ratio between a major axis and a minor axis on the cross section is 3 to 10.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a material for agricultural greenhouse curtains. [Background technology]

[0002] Conventionally, nonwoven fabrics that are breathable, water-permeable, and have heat-retaining properties have been used as materials for agricultural greenhouse curtains. Agricultural greenhouse curtains made of this nonwoven fabric material are used to maintain temperatures inside greenhouses suitable for growing crops, such as by preventing temperature drops at night in winter and daytime temperature increases in summer. Furthermore, they are required to be able to introduce a sufficient amount of sunlight into the greenhouse when in use.

[0003] A known agricultural greenhouse curtain material that meets these requirements is that described in Patent Document 1. The agricultural greenhouse curtain material described in Patent Document 1 has a foam resin coating applied to one side of the fabric, thereby improving heat-shielding properties in particular. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5812635 specification Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to further improve the technology described in Patent Document 1, thereby obtaining an agricultural greenhouse curtain material that can more reliably achieve both light transmission and heat blocking properties compared to the material described in Patent Document 1. [Means for solving the problem]

[0006] To achieve this object, the agricultural greenhouse curtain material of the present invention is characterized in that acrylic hollow particles or glass hollow particles are held in a dispersed state on both surfaces and inside of a polyester continuous fiber nonwoven fabric.

[0007] According to the agricultural greenhouse curtain material of the present invention, it is preferable that the acrylic hollow particles or glass hollow particles are held in the polyester continuous fiber nonwoven fabric by a binder.

[0008] According to the agricultural greenhouse curtain material of the present invention, it is preferable that the polyester continuous fibers constituting the polyester continuous fiber nonwoven fabric have a flat cross-sectional shape and that the ratio of the major axis to the minor axis in the cross section, i.e., major axis / minor axis, is 3 to 10. [Effects of the Invention]

[0009] According to the agricultural greenhouse curtain material of the present invention, acrylic hollow particles or glass hollow particles are held in a dispersed state on both surfaces and inside of the polyester continuous fiber nonwoven fabric, thereby reliably achieving both light transmission and heat blocking properties. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an enlarged image showing the surface of the agricultural greenhouse curtain materials of Examples 1 to 3 and Comparative Example 1. [Figure 2] 1 is an enlarged image showing the surface of the agricultural greenhouse curtain material of Comparative Example 2. [Figure 3] 1 is an image showing an enlarged cross section of agricultural greenhouse curtain materials of Examples 1 to 3 and Comparative Example 1. [Figure 4] 10 is an enlarged image showing a cross section of the agricultural greenhouse curtain material of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] The polyester continuous fiber nonwoven fabric for forming agricultural greenhouse curtain materials of the present invention has constituent fibers formed from polyester polymers. The polyester polymer is a composite of an acid component and an alcohol component. Examples of the acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalene-2,6-dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and their esters. Examples of the alcohol component include diol compounds such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, and cyclohexane-1,4-dimethanol. Examples of the polyester polymer include homopolyesters and copolymer polyesters synthesized from the above-mentioned acid and alcohol components. The polyester polymer may contain or be copolymerized with paraoxybenzoic acid, 5-sodiumsulfoisophthalic acid, polyalkylene glycol, pentaerythritol, bisphenol A, and the like. Furthermore, the polyester polymer may be an aliphatic polyester, in addition to aromatic polyesters.

[0012] Furthermore, any additives such as a matting agent, a pigment, a flame retardant, a deodorizer, an antistatic agent, an antioxidant, an ultraviolet absorber, and an antibacterial agent may be added to the polyester polymer within a range that does not impair the object of the present invention.

[0013] The fibers constituting the polyester continuous fiber nonwoven fabric are thermally bonded and fixed together by thermocompression-bonded portions. The thermocompression-bonded portions are formed in a scattered dot pattern by thermal embossing or ultrasonic fusion. The shape of each thermocompression-bonded portion may be any shape, such as a circle, ellipse, diamond, triangle, weave, cross, or lattice. In consideration of the flexibility of the nonwoven fabric, the thermocompression-bonded portions are not continuous linear or connected without being separated by non-thermocompression-bonded portions, but are separated by non-thermocompression-bonded portions and exist in a scattered dot pattern as described above. The area of ​​each thermocompression-bonded portion is 0.2 to 3 mm. 2It is preferable that the area ratio of the thermocompression bonded portion to the area of ​​the nonwoven fabric is 10% or more and 30% or less. If it is less than 10%, it is difficult to achieve a balance between excellent mechanical properties, breathability, and rigidity. If it exceeds 30%, the fabric tends to lose flexibility, making it difficult to handle and unfold as an agricultural greenhouse curtain material.

[0014] The cross section of the fibers constituting the polyester continuous fiber nonwoven fabric is not particularly limited as long as it satisfies the above-mentioned performance requirements. However, from the viewpoint of the light transmittance of the nonwoven fabric, it is preferable that the cross section be flat and that the ratio of the major axis to the minor axis (major axis / minor axis), which indicates the flatness, be 3 to 10. The term "flat" as used here includes an ellipse. If this ratio is less than 3, the flatness is low, increasing diffuse reflection when light is irradiated, which tends to result in a decrease in light transmittance. On the other hand, if this ratio exceeds 20, the degree of irregularity of the fiber cross section is too high, which tends to impair the spinning stability of the fiber. For this reason, it is more preferable that the ratio of the major axis to the minor axis of the fiber cross section be 4 to 9. On the other hand, if the fiber cross section is, for example, round (including hollow), it is more likely to fluff during use than a flat shape, resulting in a less favorable appearance. On the other hand, if the cross section is irregular other than flat, it increases diffuse reflection when light is irradiated, which tends to result in a decrease in light transmittance.

[0015] Instead of or in addition to adding an additive to the polyester polymer as described above, any agent such as a flame retardant, an antifouling agent, a deodorizer, an antibacterial agent, an ultraviolet absorber, a light stabilizer, an antioxidant, a hydrophilic agent, or an antistatic agent may be applied to the nonwoven fabric by coating or the like, as long as the object of the present invention is not impaired.

[0016] The polyester continuous fiber nonwoven fabric constituting the agricultural greenhouse curtain material of the present invention has a basis weight of 40 to 70 g / m 2 The fineness of the constituent fibers of the nonwoven fabric is preferably 2 to 9 decitex.

[0017] Polyester continuous fiber nonwoven fabrics can be produced by the following method. First, the continuous fibers that make up the nonwoven fabric can be melt-spun using a commonly used spinneret. Alternatively, the nonwoven fabric can be produced by the so-called spunbond method. For example, a continuous fiber bundle is drawn while being drawn using air pressure, electrostatically opened by a method such as corona discharge, and deposited on a moving collecting surface to form a web, which can then be thermally embossed.

[0018] The pulling speed when taking up the continuous fiber bundle is preferably set to 2000 to 5000 m / min, more preferably 3000 to 5000 m / min. If the pulling speed is less than 2000 m / min, molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the resulting nonwoven fabric tends to be poor. On the other hand, if the pulling speed exceeds 5000 m / min, the spinning stability tends to be poor.

[0019] The numerous continuous fibers that have been drawn and attenuated are opened by a known opening device, and then opened and deposited on a moving collecting surface such as a screen conveyor to form a nonwoven web. This nonwoven web is then passed through a thermal embossing device and subjected to thermal embossing to form a nonwoven fabric.

[0020] The shape of the tip of the convex portion of the embossing roll in the thermal embossing device corresponds to the shape of the above-mentioned thermally bonded portion.

[0021] The acrylic hollow particles or glass hollow particles used to form the agricultural greenhouse curtain material of the present invention are described below. The hollow particles dispersedly held on both surfaces and inside the polyester continuous fiber nonwoven fabric are particles having an outer shell and a hollow center. By holding the hollow particles dispersedly inside and on the surface of the polyester continuous fiber nonwoven fabric, the gas contained inside the hollow particles provides an insulating effect, thereby improving heat retention and heat shielding properties.

[0022] The size of the acrylic hollow particles or glass hollow particles is not particularly limited, but the average particle size measured by particle size distribution measurement (Coulter method) is preferably in the range of 5 to 20 μm, more preferably 6 to 16 μm. The particle size distribution should be approximately 2 to 30 μm. Considering the proportion and size of voids in the resulting material and the retention and dispersibility of hollow particles within the nonwoven fabric, the particle size of the hollow particles is preferably similar to or smaller than the diameter of the fibers that make up the polyester continuous fiber nonwoven fabric.

[0023] The hollow ratio of the acrylic hollow particles or glass hollow particles is not particularly limited, but is preferably 20 to 80%.

[0024] The amount of hollow particles held in the polyester continuous fiber nonwoven fabric is preferably a mass ratio of nonwoven fabric to hollow particles of (nonwoven fabric) / (hollow particles) = 100 / 0.3 to 100 / 5. If the ratio of hollow particles to 100 parts by mass of nonwoven fabric is less than 0.3 parts by mass, it becomes difficult to achieve the intended effects of the present invention. On the other hand, if the ratio of hollow particles exceeds 5 parts by mass, there is a risk that the hollow particles will fall off, although this depends on the amount of binder (described below). If the amount of binder is increased to prevent the hollow particles from falling off, the curtain material will become hard and tend to be difficult to handle.

[0025] The acrylic hollow particles are preferably thermally expandable. By having thermal expandability, the amount of gas in the particles increases, thereby further improving the heat insulating effect. The means for thermally expanding the hollow particles is not particularly limited, and examples thereof include ordinary heating means.

[0026] According to the present invention, acrylic hollow particles or glass hollow particles are held in a dispersed state on both surfaces and in the interior of a polyester continuous fiber nonwoven fabric. Here, "dispersed state" refers to a state in which the acrylic hollow particles or glass hollow particles are present and scattered evenly on one surface, the other surface, and the interior of the polyester continuous fiber nonwoven fabric. This also refers to a state in which the acrylic hollow particles or glass hollow particles are scattered evenly on both surfaces, and the interior of the polyester continuous fiber nonwoven fabric.

[0027] The method for maintaining acrylic hollow particles or glass hollow particles in a dispersed state on both surfaces and within a polyester continuous fiber nonwoven fabric is not particularly limited, and various methods can be used. Among these, it is preferable that the acrylic hollow particles or glass particles be maintained in the polyester continuous fiber nonwoven fabric by a binder. The reason for this is as follows. For example, while it is possible to thermally bond the hollow particles to the polyester continuous fiber nonwoven fabric during the hot embossing process to form the nonwoven fabric, this may result in damage to the hollow particles due to heat and pressure. Furthermore, the thermal bonding process by hot embossing results in scattered thermally bonded areas, which leads to a scattered distribution of the hollow particles in the polyester continuous fiber nonwoven fabric, concentrating them in the thermally bonded areas and almost disappearing outside the thermally bonded areas, making it impossible to achieve a good dispersion state in the polyester continuous fiber nonwoven fabric.

[0028] The binder material is not particularly limited, but it is preferable to use an acrylic binder.

[0029] Examples of methods for using a binder to hold acrylic hollow particles or glass hollow particles in a dispersed state on both surfaces and inside of a polyester continuous fiber nonwoven fabric include impregnation, kiss coat roll coating, gravure roll coating, knife coating, curtain flooring coating, spray coating, dip coating, and printing.

[0030] When using these techniques, an aqueous solution containing a binder and acrylic hollow particles or glass hollow particles is prepared, and a nonwoven fabric is impregnated with or coated with this aqueous solution, allowing the aqueous solution, i.e., the binder and hollow particles, to be easily dispersed and distributed throughout both surfaces and the interior of the nonwoven fabric. In contrast, the technique described in Patent Document 1, as is clear from the description of Comparative Example 2 described below, is limited to a method in which an acrylic resin as a coating resin is mixed with hollow particles and the resulting mixture is coated on the surface of the nonwoven fabric. However, this method makes it difficult to distribute the coating mixture throughout the interior of the nonwoven fabric or on the side opposite the coated surface. Furthermore, coating processes are difficult to perform online on a production line for agricultural greenhouse curtain materials, and therefore require time-consuming offline processing. In contrast, impregnation processes using an aqueous solution, for example, can be performed online on a production line for agricultural greenhouse curtain materials, resulting in significantly improved manufacturability compared to offline processing of the coating mixture. [Example]

[0031] The present invention will now be described in detail with reference to examples. However, the present invention is not limited to these examples. In the following examples and comparative examples, the respective property values ​​were measured by the following methods.

[0032] (1) Weight (g / m 2 ): Ten sample pieces measuring 5 cm wide x 20 cm long were prepared, and the mass (g) of each sample piece was weighed under standard conditions. The average value obtained was converted into a value per unit area to determine the basis weight (g / m) of the nonwoven fabric. 2 ) was decided.

[0033] (2) Ratio of major axis to minor axis of fiber cross section (major axis / minor axis): This was determined by measuring the major axis and minor axis sizes from the fiber cross section shown in the enlarged images of the cross section of the nonwoven fabric shown in Figures 3 and 4, and calculating the ratio of major axis to minor axis from the measurement results.

[0034] (3) Light transmittance (%): Five test pieces measuring 20 cm wide x 20 cm long were prepared, the illuminance of the light source was adjusted to 2000 lx, and the light shading rate (%) was measured in accordance with JIS-L-1913, Section 6.12. The average value of five points calculated from the obtained light shading rates was taken as the light transmittance. Note that the light transmittance (38.1%) of the agricultural greenhouse curtain material in Comparative Example 1 described below was used as the standard, and the differences from these standard light transmittances were calculated for the other Examples and Comparative Examples.

[0035] (4) Heat-shielding property (°C): A thermometer was placed at the inside bottom of a rectangular box-shaped polystyrene foam container measuring 49 cm in length, 37 cm in width, 14 cm in height, and 1.5 cm in thickness. The opening at the top of the container was covered with a sample measuring 50 cm in length and 40 cm in width, and the sample was heated from a height of 20 cm from the sample using a reflector lamp with an illuminance of 10,000 lx. The measurement time was 45 minutes, with measurements taken every minute. The highest value was taken as the maximum temperature, and the average of all measurements was taken as the average temperature. Note that the maximum temperature (69.4°C) of the agricultural greenhouse curtain material in Comparative Example 1 described below was used as the standard, and the differences from this standard temperature were calculated for the other Examples and Comparative Examples.

[0036] Example 1 The polyester polymer used to make the fibers was polyethylene terephthalate with a melting point of 258°C and an intrinsic viscosity of 0.70. This polyethylene terephthalate was melted using an extruder and melt-spun to form a flat cross section with a long-diameter to short-diameter ratio (long diameter / short diameter) of 4.12 / 1. After cooling, the spun yarn was taken up at a speed of 5000 m / min using an air sucker, opened using a known fiber opener, and collected and deposited on a moving collection surface to form a nonwoven web composed of continuous fibers. The single fiber fineness of the continuous fibers was 4.8 dtex.

[0037] Next, the web was passed through a heat embossing device consisting of an embossing roll and a smooth-surfaced metal roll to be heat-treated, and the weight of the web was reduced to 48 g / m 2 The heat embossing conditions were a surface temperature of 200°C for both rolls.2 The woven pattern has a pressure contact density of 64 points / cm 2 The pressure contact area ratio was 37%.

[0038] The obtained continuous fiber nonwoven fabric was impregnated with an aqueous solution containing 1% by mass of acrylic hollow particles (Sekisui Plastics Co., Ltd., "Techpolymer," average particle size measured by the Coulter method: 7.8 μm, particle size distribution: 2-17 μm), 33% by mass of an acrylic binder (DIC Corporation, "Boncoat U-970E"), and 5% by mass of a weathering agent (Dai-ichi Kogyo Seiyaku Co., Ltd., "Uniguard E-400"), and then dried at 150°C for 5 minutes to obtain a fabric with a basis weight of 55 g / m. 2 We obtained agricultural greenhouse curtain materials.

[0039] In this material, the amount of hollow particles held in the polyester continuous fiber nonwoven fabric was (nonwoven fabric) / (hollow particles)=100 / 0.38, in terms of the mass ratio of the nonwoven fabric to the hollow particles.

[0040] Example 2 The amount of acrylic hollow particles (Sekisui Plastics Co., Ltd., "Techpolymer") in the aqueous solution was changed to 3 mass % compared to Example 1. Otherwise, an agricultural greenhouse curtain material was obtained in the same manner as Example 1.

[0041] In this material, the amount of hollow particles held in the polyester continuous fiber nonwoven fabric was (nonwoven fabric) / (hollow particles)=100 / 1.06, in terms of the mass ratio of the nonwoven fabric to the hollow particles.

[0042] Comparative Example 1 Unlike Example 1, no hollow particles were used. Except for this, an agricultural greenhouse curtain material was obtained in the same manner as in Example 1.

[0043] Example 3 Compared to Example 1, the hollow particles were changed to glass hollow particles (Potters Barodini "Sphericel 110P8", mean particle size 10.1 μm by Coulter method, particle size distribution 2 to 32 μm), and the amount of glass hollow particles in the aqueous solution was changed to 5 mass %. A material for agricultural greenhouse curtains was obtained in the same manner as in Example 1 except for the above.

[0044] In this material, the amount of hollow particles held in the polyester continuous fiber nonwoven fabric was (nonwoven fabric) / (hollow particles)=100 / 1.69, in terms of the mass ratio of the nonwoven fabric to the hollow particles.

[0045] Comparative Example 2 The example 1 of Patent Document 1 was used as Comparative Example 4. That is, a spunbond nonwoven fabric (basis weight: 50 g / m) composed of polyethylene terephthalate fiber (fineness: 3.9 decitex, fiber cross section: round cross section) and copolymer polyester fiber (fineness: 2.8 decitex, round cross section) was used. 2 The blending ratio of the two fibers was (polyethylene terephthalate fiber):(copolymer polyester fiber)=70:30 by mass. The thickness of the nonwoven fabric was 282 μm, and the apparent density was 0.177 g / cc.

[0046] An acrylic resin used as a coating resin, which had been foamed to double its volume by adding a foaming agent, was mixed with hollow particles (thermal-expandable acrylic "Matsumoto Microsphere F F-80" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) in a mass ratio of 65 / 35 and coated onto the surface of the nonwoven fabric to obtain an agricultural greenhouse curtain material.

[0047] The properties of the agricultural greenhouse curtain materials of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1.

[0048] [Table 1]

[0049] The differences in light transmittance and heat shielding property were calculated based on the nonwoven fabric of Comparative Example 1 to which no hollow particles were added.

[0050] In comparison with Comparative Example 1, Example 1 had almost the same light transmittance and improved heat shielding properties.

[0051] In Example 2, the heat shielding property was improved compared to Comparative Example 1, but the light transmittance was slightly decreased, but the light transmittance was sufficient for practical use.

[0052] In Example 3, the heat shielding property was improved compared to Comparative Example 1, but the light transmittance was slightly decreased, but the light transmittance was sufficient for practical use.

[0053] In comparison with Comparative Example 1 and Examples 1 to 3, Comparative Example 2 was significantly superior in heat shielding properties, but was significantly inferior in light transmittance.

[0054] Figures 1 and 2 are enlarged images showing the surfaces of agricultural greenhouse curtain materials of Examples and Comparative Examples. Figure 1(a) is for Comparative Example 1, Figure 1(b) is for Example 1, Figure 1(c) is for Example 2, and Figure 1(d) is for Example 3. Figure 2(a) is for the coated side of the agricultural greenhouse curtain material of Comparative Example 2, and Figure 2(b) is for the side opposite to the coated side, i.e., the uncoated side, of the agricultural greenhouse curtain material of Comparative Example 2.

[0055] In Comparative Example 1 in Figure 1(a), hollow particles are not used and therefore cannot be confirmed, but it is clear that the surface of the flat cross-section fiber is flat.

[0056] In Figures 1(b), 1(c), and 1(d) of Examples 1, 2, and 3, it can be seen that spherical hollow particles are present in the gaps between the fibers. Comparing Figures 1(b) and 1(c), it can be seen that a larger number of hollow particles are present in Example 2 (Figure 1(c)), which has a greater amount of hollow particles than Example 1 (Figure 1(b)).

[0057] Regarding the images of Comparative Example 2 in Figures 2(a) and 2(b), a large number of hollow particles can be seen in the image of the coated surface in Figure 2(a), whereas the number of hollow particles seen in the image of the uncoated surface in Figure 2(b) is smaller than in the image of Figure 2(a).

[0058] Figures 3 and 4 are enlarged images showing the cross sections of the agricultural greenhouse curtain materials of Examples and Comparative Examples. Figure 3(a) shows the agricultural greenhouse curtain material of Comparative Example 1, Figure 3(b) shows the agricultural greenhouse curtain material of Example 1, Figure 3(c) shows the agricultural greenhouse curtain material of Example 2, Figure 3(d) shows the agricultural greenhouse curtain material of Example 3, and Figure 4 shows the agricultural greenhouse curtain material of Comparative Example 2.

[0059] In Comparative Example 1 in FIG. 3(a), the flat cross-sectional fibers are visible, but hollow particles cannot be confirmed because they are not used.

[0060] In Figures 3(b), (c), and (d) of Examples 1, 2, and 3, it can be seen that spherical hollow particles are present in the gaps between the flat cross-sectional fibers. Comparing Figures 3(b) and (c), it can be seen that Example 2 (Figure 3(c)), which has a greater amount of hollow particles than Example 1 (Figure 3(b)), has a larger number of hollow particles.

[0061] Furthermore, from the images in Figures 1(b)(c)(d) and 3(b)(c)(d), it can be seen that in Examples 1, 2, and 3, hollow particles are present to a similar extent not only on the surface of the agricultural greenhouse curtain materials but also inside them, and that they are well dispersed both on the surface and inside.

[0062] The agricultural greenhouse curtain material in Figure 4 was made by coating a nonwoven fabric with acrylic resin containing hollow particles, so the amount of hollow particles present inside the nonwoven fabric in Figure 4 was lower than on the coated surface in Figure 2(a).

Claims

1. An agricultural greenhouse curtain material characterized in that acrylic hollow particles or glass hollow particles are held in a dispersed state on both surfaces and inside of a polyester continuous fiber nonwoven fabric.

2. 2. The agricultural greenhouse curtain material according to claim 1, wherein the acrylic hollow particles or the glass hollow particles are held in a polyester continuous fiber nonwoven fabric by a binder.

3. 3. The agricultural greenhouse curtain material according to claim 1, wherein the polyester continuous fibers constituting the polyester continuous fiber nonwoven fabric have a flat cross-sectional shape, and the ratio of the major axis to the minor axis in the cross section, i.e., major axis / minor axis, is 3 to 10.

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