WO2018084156A1 - Agricultural sheet - Google Patents

Abstract

Provided is an agricultural sheet having a base sheet containing a polyolefin resin, a light stabilizer, and an inorganic filler, wherein the inorganic filler contains at least one of calcium carbonate and titanium oxide and the light stabilizer contains an NOR hindered amine light stabilizer.

Description

Agriculture sheet

This disclosure relates to agricultural sheets.

Agricultural sheets are used, for example, as members for covering soil and crops, and members of agricultural houses. The agricultural sheet imparted with light reflectivity can be used, for example, to eliminate light shortage in the house, promote coloring of harvested products, suppress ground temperature, and take measures against weeds.

Patent Document 1 discloses an agricultural sheet including a sheet base material and a light reflection layer provided on one surface of the sheet base material, and the sheet base material has an average diameter of 1 μm to 50 μm. A porous thermoplastic resin sheet having a porosity in the range of 35% to 60% and a thickness in the range of 30 μm to 90 μm. An agricultural sheet having a thickness in the range of 0.5 μm to 4 μm is disclosed.

JP 2014-233206 A JP 2011-236369 A Japanese Patent No. 4587488 JP 2013-144265 A Japanese Patent Laid-Open No. 10-219004 Japanese Patent No. 3524227

Agricultural sheets may be exposed to acidic environments such as acid rain, pesticide spraying, and sulfur fumigation. It is desired that the weather resistance is good even in such a harsh environment.

This disclosure has been made in view of the above circumstances, and its main purpose is to provide an agricultural sheet with good weather resistance.

In the present disclosure, a base sheet containing a polyolefin-based resin, a light stabilizer and an inorganic filler is included, the inorganic filler includes at least one of calcium carbonate and titanium oxide, and the light stabilizer is NOR. An agricultural sheet containing a type hindered amine light stabilizer is provided.

The agricultural sheet of the present disclosure has an effect that the weather resistance is good.

It is a schematic sectional view which illustrates an agricultural sheet of this indication. It is a schematic sectional view which illustrates an agricultural sheet of this indication. It is a schematic sectional view which illustrates an agricultural sheet of this indication. It is a schematic sectional drawing which illustrates the manufacturing method of the agricultural sheet of this indication. It is a schematic sectional drawing explaining a punch test. It is a schematic plan view explaining a punch test.

Hereinafter, the agricultural sheet of the present disclosure will be described in detail. In the present disclosure, “sheet” and “film” may be used synonymously.

FIG. 1 is a schematic cross-sectional view showing an example of the agricultural sheet of the present disclosure. An agricultural sheet 10 in FIG. 1 has a base sheet 1. Moreover, the base sheet 1 contains a polyolefin resin, a light stabilizer, and an inorganic filler. The light stabilizer includes a NOR-type hindered amine light stabilizer. The inorganic filler contains at least one of calcium carbonate and titanium oxide. FIG. 2 is a schematic cross-sectional view illustrating another example of the agricultural sheet of the present disclosure. An agricultural sheet 10 in FIG. 2 includes a base sheet 1 and a reinforcing sheet 2 located on one surface side of the base sheet.

According to the present disclosure, the base sheet contains a polyolefin resin, a NOR-type hindered amine light stabilizer and an inorganic filler, whereby an agricultural sheet having good weather resistance can be obtained.

The agricultural sheet of the present disclosure is preferably a sheet with little deterioration with respect to a predetermined weather resistance test. The “weather resistance test” in the present disclosure means that the sample is immersed in a 5% by mass aqueous solution of sulfurous acid for 72 hours, and the sample after the acid immersion treatment has an irradiance of 90 mW / cm ² or more and 100 mW / cm ² or less. A metal halide lamp type weather resistance test (equipment standard: JTMG-01: 2000, Japan Testing Machine Industry Association) under certain conditions. Since the irradiance varies somewhat depending on the device, the width is set to 90 mW / cm ² or more and 100 mW / cm ² or less. Further, the irradiation time of the metal halide lamp varies depending on the evaluation target, but is, for example, a maximum of 300 hours.

For example, when measuring the reflectance of visible light, prepare an agricultural sheet before dipping in an aqueous sulfite solution (before acid immersion) and an agricultural sheet after a weather resistance test (irradiation time of 300 hours). By measuring the rate, the degree of deterioration of the agricultural sheet can be evaluated.

In addition, you may perform a weather resistance test using another acid aqueous solution instead of a sulfurous acid aqueous solution. Examples of acids used in other acid aqueous solutions include sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, and nitrous acid. These acids are appropriately set according to the environment in which the agricultural sheet is expected to be used (for example, the type of agricultural chemical that adheres to the agricultural sheet). The pH of the aqueous acid solution is preferably 1 or more and 2 or less.

As described above, the agricultural sheet may be exposed to an acidic environment such as acid rain, agricultural chemical application, and sulfur fumigation. At this time, the conventional hindered amine light stabilizer is inactivated and the weather resistance may be lowered. On the other hand, it can be set as an agricultural sheet with favorable weather resistance by using the NOR type hindered amine light stabilizer with favorable acid resistance.

For example, Patent Document 2 describes a polyolefin resin film containing a NOR-type hindered amine light stabilizer, but it is a film mainly used for a decorative sheet and has a completely different usage environment from an agricultural sheet. As described above, since the agricultural sheet receives a lot of ultraviolet rays in addition to being exposed to an acidic environment, it can be said that it is a very severe use environment. For example, in the example of Patent Document 2, the influence of acid immersion treatment is evaluated in the column of “color change by NOx gas”, and the influence of ultraviolet rays is evaluated in the column of “weather resistance”. It is an independent evaluation. Although these evaluations are suitable for performance evaluation of decorative sheets, they are not suitable for performance evaluation of agricultural sheets used in harsh environments, and it is difficult to judge the effectiveness as agricultural sheets. On the other hand, in the above weather resistance test, the sample after the acid immersion treatment is irradiated with ultraviolet rays, and it can be confirmed that the agricultural sheet of the present disclosure has good weather resistance even in a severe use environment.

Moreover, since the base material sheet in this indication contains an inorganic filler, compared with the sheet | seat which does not contain an inorganic filler, a weather resistance falls easily. For example, when an agricultural sheet is stretched and used, minute voids due to the inorganic filler are generated inside the base sheet, and acid remains in the voids, so that the light stabilizer is likely to deteriorate. . Such a problem becomes more prominent as the content of the inorganic filler increases. On the other hand, in the present disclosure, by using a NOR-type hindered amine light stabilizer having good acid resistance, it is possible to suppress deterioration even if an acid remains, and as a result, it is possible to suppress deterioration of weather resistance.
Hereinafter, the agricultural sheet of the present disclosure will be described for each configuration.

1. Base Material Sheet The base material sheet contains a polyolefin resin, a light stabilizer, and an inorganic filler. The light stabilizer includes a NOR-type hindered amine light stabilizer, and the inorganic filler includes at least one of calcium carbonate and titanium oxide. The base sheet may be an unstretched sheet or a stretched sheet (uniaxially stretched sheet, biaxially stretched sheet, etc.).

(1) NOR type hindered amine light stabilizer The NOR type hindered amine light stabilizer is a light stabilizer excellent in acid resistance. An example of a NOR-type hindered amine light stabilizer is a compound containing a group represented by the general formula (1).

In the general formula (1), R is a substituted or unsubstituted hydrocarbon group or an acyl group. Examples of R include an alkyl group, an alkenyl group, an alkylene group, a cycloalkyl group, a bicycloalkyl group, a phenyl group, a naphthyl group, a phenylalkyl group, an alkyl group-substituted phenyl group, a hydroxyl group-substituted alkyl group, an acyl group, and an alkoxy-substituted alkyl. Group, a thioalkoxy group-substituted alkyl group, and the like. In addition, * and ** in General formula (1) have shown the state which can couple | bond with another element.

Other examples of NOR-type hindered amine light stabilizers include compounds represented by general formula (2) or general formula (3).

In the general formula (2), R ₁ and R ₂ are each independently a substituted or unsubstituted hydrocarbon group or an acyl group, like R in the general formula (1). Among these, R ₁ and R ₂ are preferably each independently an alkyl group having 4 to 20 carbon atoms.

In the general formula (3), R ₃ and R ₄ are each independently a substituted or unsubstituted hydrocarbon group or an acyl group in the same manner as R in the general formula (1) described above. Among these, R ₃ and R ₄ are preferably each independently an alkyl group having 4 to 20 carbon atoms. R ₅ is an alkylene group having 1 to 8 carbon atoms.

Specific examples of NOR-type hindered amine light stabilizers include, for example, Adeka Stab LA-81 manufactured by Adeka, Tinuvin 123 manufactured by BASF (Bis (2,2,6,6-tetramethyl-1- (octyloxy) decanedioate) ) -4-piperidinyl) ester) and the like.

The content of the NOR-type hindered amine light stabilizer in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, and 0.15% by mass with respect to the polyolefin resin. It may be the above. If the content of the NOR type hindered amine light stabilizer is too small, the weather resistance of the base sheet may not be improved. The content of the NOR type hindered amine light stabilizer may be, for example, more than 5% by mass with respect to the polyolefin resin. On the other hand, the content of the NOR type hindered amine light stabilizer is, for example, 20% by mass or less, may be 9.0% by mass or less, or 8.0% by mass or less with respect to the polyolefin resin. Also good. If the content of the NOR-type hindered amine light stabilizer is too large, an appearance abnormality such as a crack may occur in the base sheet.

The base sheet preferably contains a NOR-type hindered amine light stabilizer as a light stabilizer as a main component, and may further contain other light stabilizers as necessary. On the other hand, the base sheet may contain only a NOR-type hindered amine light stabilizer as the light stabilizer.

(2) Inorganic filler The base material sheet contains at least one of calcium carbonate and titanium oxide as an inorganic filler in order to enhance whiteness and light reflectivity.

The content of the inorganic filler in the base sheet is, for example, 30% by mass or more, 50% by mass or more, 55% by mass or more, and 60% by mass with respect to the polyolefin resin. It may be the above. When there is too little content of an inorganic filler, the whiteness and light reflectivity of a base material sheet may become low. On the other hand, the content of the inorganic filler is, for example, 80% by mass or less, 75% by mass or less, or 70% by mass or less with respect to the polyolefin resin. When there is too much content of an inorganic filler, the flexibility of a base material sheet may become low.

Further, the base sheet preferably contains at least one of calcium carbonate and titanium oxide as an inorganic filler as a main component, and further includes talc, titanium oxide, titanium oxide / antimony oxide / nickel oxide solid solution as necessary. And other inorganic fillers may be contained. Moreover, the base material sheet may have only at least one of calcium carbonate and titanium oxide as an inorganic filler.

(3) Polyolefin resin The base sheet contains a polyolefin resin. Examples of polyolefin resins include olefin homopolymers, copolymers of two or more olefins, copolymers of one or more olefins and one or more polymerizable monomers that can be polymerized with olefins, and the like. Can be mentioned. Examples of the olefin (monomer unit) include ethylene, propylene, butene, hexene and the like. The copolymer may be a binary system, a ternary system, or a quaternary system. The copolymer may be a random copolymer or a block copolymer.

Examples of polyolefin resins include polyethylene resins and polypropylene resins. Examples of the polyethylene resin include high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), and very low density polyethylene (VLDPE). These may be used alone or in combination of two or more.

Among these, high-density polyethylene and linear low-density polyethylene are preferable, and high-density polyethylene is more preferable. This is because high-density polyethylene is excellent in weather resistance and tensile strength, and a sheet containing high-density polyethylene does not sag even when it is a long roll, and appearance defects due to whitening are unlikely to occur during bending. In addition, high density polyethylene is opaque, and by adding titanium oxide and calcium carbonate, the whiteness of the film is increased, resulting in high reflectivity.

In particular, when the resin component is only a polyethylene resin, it is preferable to use at least one of high-density polyethylene and linear low-density polyethylene. In addition, high-density polyethylene is particularly suitable for sheet molding by calendering because it is excellent in heat resistance and workability during processing.

The polyethylene resin preferably has a melt flow rate (temperature 230 ° C., load 2.16 kg) measured in accordance with JIS K 7210 of 0.1 g / 10 min or more and 4.0 g / 10 min or less. More preferably, it is 4 g / 10 min or more and 2.0 g / 10 min or less. When the melt flow rate (MFR) is in the above range, it is particularly suitable for sheet forming by calendering.

The base sheet may contain a polyethylene resin as a main component of the resin component. The ratio of the polyethylene resin to the total amount of the resin components is, for example, 50% by mass or more, and may be 70% by mass or more.

On the other hand, examples of the polypropylene resin include homopolymerized polypropylene (h-PP), random copolymerized polypropylene (r-PP), block copolymerized polypropylene (b-PP), and metallocene polypropylene. These may be used alone or in combination of two or more. Among these, a random copolymer polypropylene is preferable. This is because random copolymer polypropylene is more flexible than homopolymer polypropylene or block copolymer polypropylene.

The polypropylene resin may be a copolymer of propylene and another α-olefin. Examples of other α-olefins include at least one of ethylene, butene-1, hexene-1, and heptene-1,4-methylpentene-1. The polypropylene resin preferably contains propylene as a main component of monomer units.

The polypropylene resin preferably has a melt flow rate (temperature 230 ° C., load 2.16 kg) measured in accordance with JIS K 7210, for example, 0.1 g / 10 min or more and 4.0 g / 10 min or less. 0.4 g / 10 min or more and 2.0 g / 10 min or less is more preferable. When the melt flow rate (MFR) is in the above range, it is particularly suitable for sheet forming by calendering.

The base sheet may contain a polypropylene resin as a main component of the resin component. The ratio of the polypropylene resin to the total amount of the resin components is, for example, 50% by mass or more, and may be 70% by mass or more. The base sheet may contain both a polypropylene resin and a polyethylene resin as a resin component.

Examples of other polyolefin resins include a copolymer (so-called reactor TPO) having at least one of an ethylene-propylene copolymer component and a polybutylene component and a polypropylene component.

(4) Additive The base sheet may further contain at least one of an antioxidant and an ultraviolet absorber. Since the deterioration of the antioxidant and the ultraviolet absorber is presumed to be caused by the reaction with protons in the acidic solution, the antioxidant and the ultraviolet absorber are preferably materials with high acid resistance.

(I) Antioxidant Examples of the antioxidant include a phenol-based antioxidant and a phosphorus-based antioxidant. Examples of phenolic antioxidants include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,6-di-t-butyl-4-methylphenol, 4,4′-methylene-bis (2,6-di-t-butyl) phenol, 4,4′-butylidene-bis (6-t-butyl-3-methyl) phenol, 2,2-methylene-bis ( 6-t-butyl-3-methyl) phenol, 2,2-methylene-bis (4-methyl-6-t-butyl) phenol, 4,4'-thiobis (2-methyl-6-t-butyl) phenol 4,4'-thiobis (3-methyl-2-t-butyl) phenol, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4hydroxybenzyl) Benzene, 3, 5 t- butyl-4-hydroxy -α- hydroxybenzene, n- octadecyl-3- (3,5-di -t- butyl-4-hydroxyphenyl) propionate and the like.

On the other hand, phosphorus antioxidants include, for example, trisnonylphenyl phosphite, tris (2,4-ditert-butylphenyl) phosphite, tris [2-tert-butyl-4- (3-tert-butyl- 4-hydroxy-5-methylphenylthio) -5-methylphenyl] phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, di (tridecyl) pentaerythritol diphosphite, distearyl Pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, bis (2,4-ditert-butylphenyl) pentaerythritol diphosphite, bis (2,6-ditert-butyl-4-methylphenyl) ) Pentaerythritol diphosphite, bis (2, , 6-Tritert-butylphenyl) pentaerythritol diphosphite, tetra (tridecyl) isopropylidenediphenol diphosphite, tetra (tridecyl) -4,4'-n-butylidenebis (2-tert-butyl-5-methyl) Phenol) diphosphite, hexa (tridecyl) -1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, tetrakis (2,4-ditert-butylphenyl) biphenylene di Phosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tris (2-[(2,4,8,10-tetrakis tert-butyldibenzo [d, f] [ 1,3,2] dioxaphosphin-6-yl) oxy] ethyl) amine and the like.

The content of the antioxidant in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or 0.4% by mass or more with respect to the polyolefin resin. Also good. When there is too little content of antioxidant, the weather resistance of a base material sheet may not improve. On the other hand, the content of the antioxidant in the base sheet is, for example, 5.0% by mass or less, may be 3.0% by mass or less, and may be 1.0% by mass or less with respect to the polyolefin resin. There may be. When there is too much content of antioxidant, it may lead to the appearance defect by bleed-out.

(Ii) Ultraviolet absorber Examples of the ultraviolet absorber include benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and the like. Further, examples of the benzotriazole ultraviolet absorber include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-ditert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-ditert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- ( 2-hydroxy-3-tert-butyl-5-carbooctoxyethylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dic Milphenyl) benzotriazole, 2,2'-methylenebis (4-tert-octyl-6-benzotriazolylphenol) And 2-hydroxyphenylbenzotriazole compounds.

The content of the ultraviolet absorber in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or 0.4% by mass or more with respect to the polyolefin resin. Also good. When there is too little content of a ultraviolet absorber, the weather resistance of a base material sheet may not improve. On the other hand, the content of the ultraviolet absorber in the base sheet is, for example, 5.0% by mass or less, may be 3.0% by mass or less, or 1.0% by mass or less with respect to the polyolefin resin. There may be. When there is too much content of a ultraviolet absorber, it may lead to the external appearance defect by bleeding out and the external appearance defect by coloring depending on the kind of ultraviolet absorber.

(Iii) Heavy metal deactivator The base sheet may contain a heavy metal deactivator. When the agricultural sheet is in contact with, for example, an iron pipe, the polyolefin-based resin may be decomposed due to the influence of a heavy metal element (eg, Fe element) contained in the iron pipe. Specifically, a heavy metal element forms an oxide, and the polyolefin resin may be decomposed by the catalytic action of the oxide. Examples of the heavy metal element include Fe element, Cu element, Mn element, Zn element and the like.

Heavy metal deactivators are known as copper damage inhibitors. The heavy metal deactivator is not particularly limited, and examples thereof include oxalic acid derivatives, salicylic acid derivatives, hydrazide derivatives, and the like. More specifically, trade names Eastman Inhibitor OAB H (manufactured by Eastman Kodak Company), Adekastab CDA-1 CDA-6 (manufactured by Adeka), Chele-180, Inganox MD 1024 (manufactured by BASF) and the like.

The content of the heavy metal deactivator in the base sheet is, for example, 0.05% by mass or more, may be 0.1% by mass or more, or 0.4% by mass or more with respect to the polyolefin resin. May be. If the content of the heavy metal deactivator is too small, copper damage may not be sufficiently suppressed. On the other hand, the content of the heavy metal deactivator in the base sheet is, for example, 5.0% by mass or less, may be 3.0% by mass or less, and 1.0% by mass or less with respect to the polyolefin resin. It may be. If the content of the heavy metal deactivator is too large, it may lead to poor appearance due to poor dispersion.

Also, polyethylene resins are particularly susceptible to copper damage. Therefore, when a base material sheet contains a polyethylene-type resin, it is preferable that a base material sheet contains a heavy metal deactivator further. Moreover, it is preferable that an agricultural sheet is used for the use which contacts metal members (metal member containing a heavy metal element), such as an iron pipe. That is, in this indication, an agricultural member which has an agricultural sheet and a metal member containing a heavy metal element can also be provided. As such an agricultural member, for example, a member in which an agricultural sheet is wound around a metal member can be cited.

(Iv) Others The base sheet may further contain an appropriate amount of known additives such as lubricants, heat stabilizers, pigments, modifiers, flame retardants, antistatic agents, reinforcing agents, and antifungal agents. .

The composite inorganic compound containing at least two kinds of metals selected from the base sheet, alkali metal, Mg and Al may not be contained. Moreover, the base sheet does not need to contain a benzoate compound. Further, the base sheet may not contain a hydrotalcite compound.

(5) Base Material Sheet The base material sheet may be a sheet having no voids inside, or a sheet having a void inside (porous substrate sheet). Moreover, the base sheet may have a single layer structure or a multilayer structure. When the base sheet has a multilayer structure, the resin components contained in each layer may be the same or different. As an example of a base sheet having a multilayer structure, an inner layer and two outer layers located on both sides of the inner layer, the resin components contained in the two outer layers are the same, and the resin component contained in the outer layer The base material sheet from which the resin component contained in an inner layer differs is mentioned.

The substrate sheet preferably has a high visible light reflectance. The average reflectance of visible light (wavelength of 380 nm or more and 780 nm or less) is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more. In addition, the measurement conditions of the average reflectance of visible light will be described in detail in Examples described later.

The substrate sheet preferably has a high visible light reflectance after the above-described weather resistance test (irradiation time: 300 hours). The average reflectance of visible light (wavelength of 380 nm or more and 780 nm or less) after the weather resistance test is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more. Moreover, let the visible light average reflectance of the base material sheet before acid immersion be _R0 (%), and let the visible light average reflectance of the base material sheet after a weather resistance test (irradiation time 300 hours) be _R300 (%). In this case, the value of R ₃₀₀ / R ₀ is, for example, 0.90 or more, and preferably 0.95 or more.

The substrate sheet preferably has a high tensile strength after the above-described weather resistance test (irradiation time: 300 hours). The tensile strength after the weather resistance test is, for example, larger than 7 N / 15 mm, preferably 10 N / 15 mm or more, and more preferably 15 N / 15 mm or more. In addition, about the measurement conditions of tensile strength, it mentions in full detail in the Example mentioned later.

It is preferable that the base sheet has a high spelling needle holding strength after the above-described weather resistance test (irradiation time: 300 hours). The spelling needle holding strength is the strength around the hole formed by the spelling needle penetrating when the spelling needle is inserted into the sample. The spelling needle holding strength after the weather resistance test is, for example, greater than 7N, preferably 10N or more, and more preferably 15N or more. In addition, the measurement conditions of the spelling needle holding strength will be described in detail in Examples described later.

It is preferable that the base sheet has a large elongation at break after the above-described weather resistance test (irradiation time: 300 hours). The breaking elongation after the weather resistance test is, for example, 300% or more, preferably 400% or more, and more preferably 500% or more. In addition, about the measurement conditions of breaking elongation, it mentions in full detail in the Example mentioned later. Further, when the elongation at break of the base sheet before acid immersion is E ₀ (%) and the break elongation of the base sheet after the weather resistance test (irradiation time 300 hours) is E ₃₀₀ (%), E the value of ₃₀₀ / _{E 0} is, for example, 0.50 or more, preferably 0.70 or more.

The polyolefin-based resin in the base sheet preferably has a large number average molecular weight after the above-described weather resistance test (irradiation time: 100 hours). The number average molecular weight after the weather resistance test depends on the type of the polyolefin resin, but is, for example, 20,000 or more, 30,000 or more, or 50,000 or more. In addition, about the measurement conditions of a number average molecular weight, it mentions in full detail in the Example mentioned later.

The polyolefin resin in the base sheet preferably has a large number average molecular weight maintenance rate after the above-described weather resistance test (irradiation time: 100 hours). When the number average molecular weight of the polyolefin resin before acid immersion is M ₀ and the number average molecular weight of the polyolefin resin after the weather resistance test (irradiation time 100 hours) is M ₁₀₀ , the value of M ₁₀₀ / M ₀ is For example, it is 0.50 or more, preferably 0.60 or more, more preferably 0.70 or more, and further preferably 0.90 or more.

As described above, the base sheet may be a porous base sheet. The average diameter of the voids in the porous substrate sheet is, for example, 1 μm or more and 50 μm or less, preferably 2 μm or more and 40 μm or less, and more preferably 5 μm or more and 30 μm or less. Note that the average diameter (L) of the void and the maximum diameter (M) in the direction perpendicular thereto are measured and averaged [(L + M) / 2] as the void diameter. The diameter of at least n (n is an integer of 1 or more, and preferably an integer of 100 or more) is measured, and the average value is defined as the average diameter of the voids. For example, a scanning electron microscope S-2400 manufactured by Hitachi, Ltd. can be used for cross-sectional observation of the sample.

The porosity of the porous substrate sheet is, for example, 15% or more and 70% or less, 35% or more and 60% or less, or 40% or more and 58% or less. Here, the porosity indicates the ratio of voids in the porous substrate sheet and can be calculated from the following formula.
Density of each layer = mass per m ^{2 of} each laminated layer / thickness of each laminated layer Porosity = (1−density of each layer / density of base sheet not forming void) × 100

It is preferable that the substrate sheet has high smoothness. Specifically, the arithmetic average height Sa on the substrate sheet surface is, for example, 1 μm or less, preferably 0.7 μm or less, and more preferably 0.5 μm or less. Moreover, it is preferable that the antifouling property of a base material sheet is high. Specifically, the contamination level (JIS-L-1919) of the substrate sheet surface is preferably 3 or more, more preferably 3.5 or more.

The base sheet may have at least one of moisture permeability, breathability, and water shielding. Moisture permeability refers to the property of allowing water, i.e., water vapor, to pass through, and air permeability refers to the property of allowing gas, such as carbon dioxide, to pass. A property that is not allowed.

The thickness of the base sheet is not particularly limited, but is, for example, 25 μm or more, 30 μm or more, or 40 μm or more. On the other hand, the thickness of the base sheet is, for example, 90 μm or less, and may be 80 μm or less. When the thickness of the base sheet is within the above range, for example, when the base sheet is produced by calendering, a sheet having excellent surface smoothness and high thickness accuracy can be obtained.

(6) Manufacturing method of base sheet The manufacturing method of the base sheet is not particularly limited as long as the target base sheet can be obtained. For example, the base sheet includes a polyolefin resin, a light stabilizer, and an inorganic filler. The manufacturing method which has the process of producing the resin composition to perform, and the process of forming the said resin composition into a sheet (film-izing) and producing a base material sheet is mentioned. In addition, in this indication, the manufacturing method of the base sheet for agricultural sheets which has said each process can be provided.

The production method of the resin composition is not particularly limited, but a method of producing a resin composition by melting and kneading a predetermined amount of each raw material is preferable. Examples of the apparatus used for melt kneading include a continuous kneader, a Banbury mixer, a kneader, and an extruder. The heating temperature at the time of melt kneading is, for example, 150 ° C. or more and 200 ° C. or less.

As a method for forming the resin composition into a sheet, known molding methods such as calendering and extrusion molding may be used, and calendering is particularly preferable. For example, when the thickness of the sheet is small, it is suitable for manufacturing a sheet having a uniform thickness. In addition, the calendar molding is suitable because it is easy to correspond to the size and the type of resin due to the structure of the molding machine, and can easily correspond to a small lot. Furthermore, in the present disclosure, when using a resin composition having a high content of inorganic filler, it is preferable to mold by calendering. When the inorganic filler is contained in a large amount, for example, if it is formed by extrusion molding, the surface of the obtained sheet is rough and the sheet is liable to tear. A smooth sheet can be produced. Furthermore, the superiority of calendering when using a resin composition having a high content of inorganic filler is particularly noticeable when the thickness of the base sheet is as thin as, for example, about 30 μm to 70 μm.

In calendering, for example, a base sheet can be obtained by supplying and rolling a resin composition obtained by melt-kneading to a heated calender roll. The heating temperature of the calender roll is, for example, 150 ° C. or higher and 220 ° C. or lower, and preferably 160 ° C. or higher and 190 ° C. or lower. As the calendar device, an appropriate device such as a 3-type, 4-L type, 4-inverted L-type, 4-Z type, or 6-type type may be used.

After forming the resin composition into a sheet, various surface treatments may be performed as necessary. Examples of the surface treatment include corona treatment (corona discharge treatment), plasma treatment, ultraviolet treatment, electron beam treatment (electron beam emission treatment), and the like.

2. Reinforcing sheet The agricultural sheet may have a reinforcing sheet on at least one surface side of the base sheet. The reinforcing sheet is a sheet that reinforces the base sheet. The agricultural sheet may have another layer between the base sheet and the reinforcing sheet, or may be in contact with other layers.

Reinforcing sheets usually do not contain a light stabilizer and therefore have lower weather resistance than base sheets. Since the base sheet contains a NOR type hindered amine light stabilizer having good acid resistance, it also functions as a protective layer for the reinforcing sheet.

Examples of the reinforcing sheet include nonwoven fabric and woven fabric. The material of the nonwoven fabric or woven fabric is preferably a polyolefin resin, an ester resin or an amide resin among thermoplastic resins. In addition, as the nonwoven fabric, for example, fiber orthogonal nonwoven fabric, long fiber nonwoven fabric, short fiber nonwoven fabric, wet nonwoven fabric, dry nonwoven fabric, airlaid nonwoven fabric, card nonwoven fabric, parallel nonwoven fabric, cloth nonwoven fabric, random nonwoven fabric, spunbond nonwoven fabric, meltblown nonwoven fabric , Flash spinning nonwoven fabric, chemical bond nonwoven fabric, hydroentangled nonwoven fabric, needle punch nonwoven fabric, stitch bond nonwoven fabric, thermal bond nonwoven fabric, burst fiber nonwoven fabric, tow spread nonwoven fabric, split fiber nonwoven fabric, composite nonwoven fabric, laminated nonwoven fabric, coated nonwoven fabric, laminated nonwoven fabric, etc. Is mentioned.

The fiber-orthogonal nonwoven fabric is a nonwoven fabric obtained by laminating two or more stretched films so that the stretching directions are perpendicular to each other, and examples thereof include Warif (registered trademark) manufactured by JX ANCI Corporation. The basis weight of the fiber orthogonal nonwoven fabric is preferably 5 g / m ² or more and 100 g / m ² or less, more preferably 20 g / m ² or more and 50 g / m ² or less. When the basis weight of the fiber orthogonal nonwoven fabric has the above lower limit, a reinforcing sheet having sufficient strength can be obtained. Moreover, it is preferable that the fiber diameters of a long-fiber nonwoven fabric are 3 micrometers or more and 20 micrometers or less, for example. On the other hand, the fiber diameter of the short fiber nonwoven fabric is preferably less than 3 μm, for example.

On the other hand, as another example of the reinforcing sheet, a cloth type non-woven fabric may be mentioned. Examples of the cloth type non-woven fabric include polyolefin mesh cloth disclosed in Japanese Patent Application Laid-Open No. 2007-259734. The polyolefin mesh cloth is preferably a polyethylene mesh cloth. A polyethylene mesh cloth is preferably used in consideration of, for example, adhesion in extrusion molding. The cloth nonwoven fabric preferably has a thickness of 30 μm to 100 μm, and more preferably 50 μm to 80 μm.

Cloth-type non-woven fabric is suitably used as a reinforcing sheet for the purpose of, for example, circulating air inside an agricultural house and preventing insects from entering. In addition, the cloth type non-woven fabric has excellent mechanical properties such as tear strength, and is suitably used as a reinforcing sheet. For example, the cloth type non-woven fabric is advantageous in that it is easy to control tension during lamination by the Roll to Roll method and has less curl. Furthermore, the cloth type non-woven fabric has a strength that allows edge processing, and for example, it is possible to provide eyelets on the edge processing portion.

As the woven structure of the cloth type nonwoven fabric, for example, various shapes such as plain weave, twill weave, entangled weave and imitation weave are used, but plain weave is preferable from the viewpoint of smoothness.

Cloth-type nonwoven fabric can be formed by weaving drawn yarns as warp and weft yarns. In the present disclosure, the cloth nonwoven fabric has five or more fibers along the first direction in a region of 1 inch square, and has five or more fibers along the second direction intersecting the first direction. It is preferable to have. Expressing this in terms of driving density, it can be expressed as “5 × 5 / inch or more”. The driving density can be, for example, 5 × 5 / inch or more, preferably 6 × 5 / inch or more, and more preferably 8 × 8 / inch or more. Further, the driving density can be set to 10 × 10 pieces / inch or less, for example. When the driving density has the above upper limit, it is possible to suppress an increase in manufacturing cost and a problem that the curl of the laminated product becomes too large.

The mesh in the cloth-type nonwoven fabric is preferably 0.3 mm or more in both the first direction (for example, the vertical direction) and the second direction (for example, the horizontal direction), and more preferably 0.4 mm or more. Moreover, it is preferable that it is 3 mm or less in the 1st direction (for example, vertical direction) and the 2nd direction (for example, horizontal direction), and it is preferable that it is 2 mm or less especially in the cloth type nonwoven fabric. Here, the term “mesh” refers to the width of the space between adjacent fibers in the first direction or the second direction of the mesh. When the mesh in the cloth type nonwoven fabric has the above lower limit, an increase in the light shielding rate can be suppressed. Moreover, when the mesh in a cloth type nonwoven fabric has the said upper limit, the fall of the intensity | strength of a cloth type nonwoven fabric can be suppressed.

Cloth-type non-woven fabric can be manufactured using, for example, monofilament or flat yarn. The cloth type nonwoven fabric obtained by using monofilament has high strength and good air permeability, and the cloth type nonwoven cloth obtained by using flat yarns is easy to form a cloth having a smooth surface and has good coverage. Moreover, the cloth type nonwoven fabric can be preferably obtained by heat-bonding a core-sheath composite monofilament or a multilayer composite flat yarn. The cloth type nonwoven fabric obtained by using the core-sheath composite monofilament or the multilayer composite flat yarn is made of, for example, a polyolefin having a relatively low temperature covering the surface, which is softened and melted by heating, and is bonded to each other at the cross-bonding portion of the warp and weft. It is obtained by heat sealing. With such a sealing treatment, it is possible to prevent misalignment having durability.

The core-sheath composite monofilament preferably has a structure in which a high melting point polyolefin having a relatively high melting point is used as a core layer, and a polyolefin having a lower melting point is coated on the surface of the core layer to form a sheath layer. As the core / sheath layer combination of the core / sheath composite monofilament, propylene homopolymer / propylene-ethylene block copolymer, propylene homopolymer / propylene-ethylene random copolymer, propylene homopolymer / high-density polyethylene, propylene single Polymer / low density polyethylene, propylene homopolymer layer / linear low density polyethylene, propylene-ethylene block copolymer / linear low density polyethylene, propylene-ethylene random copolymer / low density polyethylene, high density polyethylene / Examples thereof include low density polyethylene, high density polyethylene / linear low density polyethylene, and the like. More preferable combinations of the core layer / sheath layer include, for example, high-density polyethylene / low-density polyethylene and high-density polyethylene / linear low-density polyethylene from the viewpoint of heat-fusibility, strength, recycling, and the like. It is done.

The core-sheath composite monofilament is, for example, melt-kneaded polyolefin resin of each layer of the core layer and the sheath layer with an extruder, for example, supplying a core layer made of a high melting point polyolefin at a melting temperature of 160 ° C. or more and 300 ° C. or less, The outer surface is coated with a sheath layer made of a low-melting polyolefin, cooled and solidified, and then subjected to stretching treatment and further subjected to relaxation heat treatment. The draw ratio can be, for example, from 3 times to 12 times, and preferably from 5 times to 10 times.

The fineness of the core-sheath composite monofilament is, for example, preferably 30 dt or more, and more preferably 50 dt or more. Further, the fineness of the core-sheath composite monofilament is preferably, for example, 3000 dt or less, and more preferably 2000 dt or less. When the fineness of the core-sheath composite monofilament has the above lower limit, it is possible to suppress the occurrence of a problem that the fiber is too thin and the durability is lowered. Moreover, the fall of mechanical characteristics, such as tear strength as a reinforcement sheet, can be suppressed. On the other hand, when the fineness of the core-sheath composite monofilament has the above upper limit, good weaving is possible. Also, good flexibility is obtained, and sufficient adhesion with the adhesive layer is possible.

The cross-sectional area ratio (sheath layer / core layer) between the sheath layer and the core layer of the core-sheath composite filament is preferably 1/9 or more, and more preferably 2/8 or more. The cross-sectional area ratio (sheath layer / core layer) between the sheath layer and the core layer of the core-sheath composite filament is preferably, for example, 6/4 or less, and more preferably 5/5 or less. When the cross-sectional area ratio between the sheath layer and the core layer of the core-sheath composite filament has the above lower limit, the sheath component can cover the entire cross section of the core layer, and a decrease in adhesive strength can be suppressed. On the other hand, when the cross-sectional area ratio between the sheath layer and the core layer of the core-sheath composite filament has the above upper limit, a decrease in the tensile strength of the filament yarn can be suppressed.

The multi-layer composite flat yarn preferably has a multi-layer structure in which a high melting point polyolefin is used as an inner base layer and a low melting point polyolefin having a lower melting point is sandwiched between outer surface layers. Examples of the combination of the multilayer composite flat yarn include a low density polyethylene layer / high density polyethylene layer / low density polyethylene layer composite, a linear low density polyethylene layer / a high density polyethylene layer / a linear low density polyethylene layer. Examples thereof include a composite and a combination of a composite of propylene-ethylene random copolymer layer / polypropylene homopolymer layer / propylene-ethylene random copolymer layer. More preferable multi-layer composite flat yarn combinations include low-density polyethylene layer / high-density polyethylene layer / low-density polyethylene layer composite, linear low-density polyethylene layer / high-density polyethylene layer / linear chain from the viewpoint of recycling and the like. And a low-density polyethylene layer composite.

The multilayer composite flat yarn is, for example, a melt-kneaded polyolefin-based resin of each layer of the inner layer base layer and the outer layer surface layer with an extruder, for example, a base material made of a high melting point polyolefin at a melting temperature of 160 ° C. to 300 ° C. In addition to supplying a layer, a surface layer made of a low-melting-point polyolefin is coated on both the upper and lower surfaces of the base material layer, cooled and solidified, then slitted, further subjected to stretching treatment, and then subjected to relaxation heat treatment. . For example, the draw ratio is preferably 3 to 12 times.

The fineness of the multilayer composite flat yarn is, for example, preferably 100 dt or more, and more preferably 200 dt or more. Further, the fineness of the multilayer composite flat yarn is preferably, for example, 4000 dt or less, and particularly preferably 3000 dt or less. When the fineness of the multilayer composite flat yarn has the above lower limit, it is possible to suppress the occurrence of problems such as the fibers becoming too thin and the durability being lowered. On the other hand, when the fineness of the multilayer composite flat yarn has the above upper limit, good weaving becomes possible.

Further, the cross-sectional area ratio (surface layer / base material layer) between the surface layer and the base material layer of the multilayer composite flat yarn is preferably 1/9 or more, and more preferably 2/8 or more. In addition, the cross-sectional area ratio between the surface layer and the base material layer of the multilayer composite flat yarn is preferably 6/4 or less, and particularly preferably 5/5 or less. When the cross-sectional area ratio between the surface layer and the base material layer of the multilayer composite flat yarn has the above lower limit, the surface layer can sufficiently cover the base material layer and can suppress a decrease in adhesive strength. it can. On the other hand, when the cross-sectional area ratio between the surface layer and the base material layer of the multilayer composite flat yarn has the above upper limit, a decrease in the tensile strength of the filament yarn can be suppressed. Here, the cross-sectional area of the surface layer in the cross-sectional area ratio is the sum of the cross-sectional areas of the surface layers on both sides.

The reinforcing sheet preferably contains a resin. The resin may be a thermoplastic resin or a thermosetting resin, but the former is preferred. Examples of the thermoplastic resin include a polyolefin resin, an acrylic resin, a styrene resin, a vinyl fluoride resin, an amide resin, and a saturated ester resin, and among them, a polyolefin resin is preferable. In the present disclosure, the reinforcing sheet is preferably a fiber orthogonal nonwoven fabric containing a polyolefin resin. This is because heat resistance, water resistance, chemical resistance and cost are excellent.

Specific examples of the polyolefin-based resin include, for example, a polyethylene-based resin and a polypropylene-based resin, and among them, a polyethylene-based resin is preferable. Examples of the polyolefin-based resin include the polyolefin-based resins described in the above “1. Base sheet”.

As described above, acrylic resin, styrene resin, vinyl fluoride resin, amide resin, ester resin, or the like can be used as the thermoplastic resin. Examples of the acrylic resin include polymethyl acrylate, polymethyl methacrylate, and ethylene-ethyl acrylate copolymer. Examples of the styrene resin include butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polystyrene, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-acrylic acid copolymer, and the like. Is mentioned. Examples of the vinyl fluoride resin include vinyl chloride resins, polyvinyl fluoride, and polyvinylidene fluoride. Examples of the amide resin include 6-nylon, 6,6-nylon, 12-nylon, and the like. Examples of the ester resin include polyethylene terephthalate and polyprebutylene terephthalate. In addition, as the thermoplastic resin, polycarbonate, polyphenylene oxide, polyacetal, polyphenylene sulfide, silicone resin, thermoplastic urethane resin, polyether ether ketone, polyether imide, thermoplastic elastomer, or the like may be used.

Also, it is preferable that both the reinforcing sheet and the base sheet contain a polyethylene resin. For example, when an adhesive layer to be described later is provided, since the polyethylene-based resin has the same adhesiveness to the adhesive, an agricultural sheet that is firmly bonded can be obtained. Further, since the degree of expansion and contraction due to heat, moisture, and the like is close, warpage is unlikely to occur and adhesion is difficult to peel off. As a result, an agricultural sheet with high durability is obtained. Moreover, it becomes an agricultural sheet | seat with high water resistance by using a polyethylene-type resin. In addition, when both the reinforcing sheet and the base sheet contain a polyethylene resin, it becomes a recyclable agricultural sheet and has a low environmental impact during disposal. In particular, the entire agricultural sheet layer preferably contains a polyethylene resin.

Further, it is preferable that the reinforcing sheet contains a polypropylene resin and the base sheet contains a polyethylene resin. This is because the processability of agricultural sheets is improved. Specifically, since a polypropylene resin is a relatively hard resin, it is difficult to process. On the other hand, since a polyethylene-type resin is a comparatively soft resin, the processability of an agricultural sheet improves by combining a polyethylene-type resin.

Further, the reinforcing sheet may have a single layer structure or a multilayer structure. As an agricultural sheet having a single-layered reinforcing sheet, for example, as shown in FIG. 3A, an agricultural sheet having a base sheet 1, an adhesive layer 3, and a single-layered reinforcing sheet 2 in this order. 10 is mentioned.

On the other hand, as an agricultural sheet having a reinforcing sheet having a multilayer structure, for example, as shown in FIG. 3B, a base sheet 1, an adhesive layer 3, and a reinforcing sheet 2 having a multilayer structure are provided in this order. The agricultural sheet 10 is mentioned. The reinforcing sheet 2 having a multilayer structure includes a first reinforcing sheet layer 2a, a reinforcing sheet adhesive layer 4, and a second reinforcing sheet layer 2b in this order. Although not shown, the plurality of reinforcing sheet layers may be in contact (for example, fused) without interposing the adhesive layer. Moreover, the kind of adhesive layer for reinforcement sheets is not specifically limited, For example, it is the same as the content described in "3. Adhesive layer" mentioned later.

The reinforcing sheet may be a porous reinforcing sheet. When the reinforcing sheet has a multilayer structure, at least one layer constituting the reinforcing sheet may be a porous reinforcing layer.

The thickness of the reinforcing sheet is not particularly limited, but is, for example, from 10 μm to 150 μm, and preferably from 20 μm to 100 μm. In addition, when a reinforcement sheet is a multilayer structure, it is preferable that the thickness of each layer which comprises a reinforcement sheet exists in the range mentioned above. Moreover, the agricultural sheet may have a reinforcement sheet in the outermost surface, and may have in an inside.

3. Adhesive layer When the agricultural sheet has a reinforcing sheet on one side of the base sheet, the agricultural sheet may or may not have an adhesive layer between the base sheet and the reinforcing sheet. Also good. In the latter case, the base sheet and the reinforcing sheet are preferably in direct contact. Moreover, it is preferable that a contact bonding layer contains resin, such as polyolefin resin, for example. Such an adhesive layer can be obtained, for example, by extrusion coating a resin.

In extrusion coating, resins that can be melted by heat and fused to each other can be used. Examples of such resins include polyethylene resins such as low density polyethylene, medium density polyethylene, high density polyethylene, linear (linear) low density polyethylene, polypropylene resins such as polypropylene, and ethylene-vinyl acetate copolymer. Polymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, Polyolefin polymers such as polybutene polymer, polyethylene or polypropylene modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and polyvinyl acetate resins , Poly ( Data) acrylic resins, polyvinyl chloride resins can be used.

These may be used alone or in combination of two or more. Among these, polyethylene resins are suitable, low density polyethylene and linear low density polyethylene are preferable, and low density polyethylene is more preferable. Low density polyethylene is excellent in processability, excellent in adhesion to polyethylene nonwoven fabric, and inexpensive.

The polyethylene resin preferably has a melt flow rate (temperature 230 ° C., load 2.16 kg) measured in accordance with JIS K 7210 of 0.1 g / 10 min or more and 4.0 g / 10 min or less. More preferably, it is 4 g / 10 min or more and 2.0 g / 10 min or less. A melt flow rate (MFR) in the above range is particularly suitable for extrusion coating.

Moreover, in order to strengthen adhesiveness with a reinforcement sheet with a base material sheet, you may coat an anchor coating agent on a base material sheet, for example, and may provide an anchor coating agent layer. Examples of the anchor coating agent that forms the anchor coating agent layer include organic titanium anchor coating agents such as alkyl titanates, isocyanate anchor coating agents, polyethyleneimine anchor coating agents, and polybutadiene anchor coating agents. In the present disclosure, similarly to the above, the anchor coating agent is coated by, for example, roll coating, gravure coating, knife coating, dip coating, spray coating, or other coating methods, and the solvent, diluent, etc. are dried. An anchor coating agent layer can be formed. In the above, the application amount of the anchor coating agent is preferably 0.1 g / m ² or more and 5 g / m ² or less (dry state).

In the present disclosure, as an adhesive for laminating to form an anchor coating agent, for example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate, or hexamethylene diisocyanate , Polyether polyurethane resins and polyesters obtained by reaction of polyfunctional isocyanates such as aliphatic polyisocyanates such as xylylene diisocyanate with hydroxyl group-containing compounds such as polyether polyols, polyester polyols and polyacrylate polyols It is preferable to use a laminating adhesive mainly composed of a polyurethane polyurethane resin or a polyacrylate polyurethane resin.

The anchor coating agent layer can form a thin film that is soft, flexible, and flexible, and can improve its tensile elongation. Moreover, it acts as a film having flexibility, flexibility and the like on the base material sheet, improves the suitability of base material sheet processing at the time of laminating, and can prevent peeling failure during use.

In addition, it is preferable that the anchor coating agent layer in the present disclosure has a tensile elongation of 100% or more and 300% or less based on JIS standard K7113. The tight adhesion between the base material sheet and the reinforcing sheet can be improved by the tensile elongation of the anchor coating agent layer. Therefore, the laminate strength between the base sheet and the reinforcing sheet can be increased.

On the other hand, the adhesive layer in the present disclosure may be a layer containing an adhesive described later. Such an adhesive layer can be obtained, for example, by applying an adhesive composition containing an adhesive. The type of adhesive is not particularly limited. For example, polyether adhesive, polyester adhesive, polyurethane adhesive, vinyl adhesive, (meth) acrylic adhesive, polyamide adhesive, epoxy adhesive Materials, rubber adhesives and the like. The adhesive may be a one-component curable type or a two-component curable type.

Examples of the polyether adhesive include polyether polyurethane. Polyether polyurethane is obtained by the reaction of polyether polyol and polyisocyanate. Examples of the polyether polyol include a compound obtained by polymerizing an oxirane compound such as ethylene oxide or propylene oxide using a polyhydric alcohol such as ethylene glycol, 1,2-propanediol or glycerin as a polymerization initiator.

Examples of the polyisocyanate include 1,6-hexamethylene diisocyanate, methylene diisocyanate, trimethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, 1, Aliphatic isocyanates such as 2-propylene diisocyanate, isopropylene diisocyanate, and 1,3-butylene diisocyanate; 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methyl Alicyclic isocyanates such as -2,6-cyclohexane diisocyanate; m-phenylene diisocyanate, p Phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, aromatic isocyanates such as naphthylene diisocyanate and the like.

Examples of the polyester adhesive include polyester polyurethane. Polyester polyurethane is obtained by the reaction between polyester polyol and polyisocyanate. Examples of the polyester polyol include a polyester polyol obtained by reacting a polyvalent carboxylic acid and a polyhydric alcohol, and a polyester polyol obtained by ring-opening polymerization of a lactone ring. Examples of the polyvalent carboxylic acid include saturated aliphatic polyvalent carboxylic acids such as adipic acid, azelaic acid, succinic acid, and sebacic acid; unsaturated aliphatic polyvalent carboxylic acids such as fumaric acid and maleic acid; 1,4- Examples thereof include alicyclic polycarboxylic acids such as cyclohexanedicarboxylic acid; aromatic polycarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid.

Examples of the polyhydric alcohol include aliphatic and alicyclic polyhydric alcohols, and aromatic polyhydric alcohols. Specifically, ethylene glycol, diethylene glycol, 1,3-propylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, xylylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, Examples include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and the like. The polyisocyanate is as described above.

Further, polyether polyester polyurethane may be used as an adhesive. The polyether polyester polyurethane is a polyether adhesive and a polyester adhesive. The polyether polyester polyurethane is obtained by reacting a polyether ester polyol with a polyisocyanate. As polyether ester polyol, the polyether ester polyol obtained by making said polyhydric carboxylic acid react with the said polyether polyol is mentioned, for example.

The thickness of the adhesive layer is, for example, 20 μm or less. For example, when the adhesive layer is formed by extrusion coating, the thickness of the adhesive layer is preferably 10 μm or more and 20 μm or less. For example, when forming an adhesive layer by applying an adhesive composition, the thickness of the adhesive layer is preferably 10 μm or less, for example.

4). Agricultural sheet The agricultural sheet has at least a base sheet. The agricultural sheet may be a base sheet alone or may further have a reinforcing sheet. The agricultural sheet may have a base sheet on the outermost surface.

It is preferable that the agricultural sheet has a high visible light reflectance. The average reflectance of visible light (wavelength of 380 nm or more and 780 nm or less) is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more.

The agricultural sheet preferably has a high visible light reflectance after the above-described weather resistance test (irradiation time: 300 hours). The average reflectance of visible light (wavelength of 380 nm or more and 780 nm or less) after the weather resistance test is, for example, 70% or more, preferably 80% or more, and more preferably 90% or more. Moreover, when the visible light average reflectance of the agricultural sheet before acid immersion is R ₀ (%), and the visible light average reflectance of the agricultural sheet after the weather resistance test (irradiation time 300 hours) is R ₃₀₀ (%) , R ₃₀₀ / R ₀ is, for example, 0.90 or more and preferably 0.95 or more. In addition, about the measurement conditions of tensile strength, it mentions in full detail in the Example mentioned later.

It is preferable that the agricultural sheet (particularly, the agricultural sheet having a reinforcing sheet) has a high tensile strength after the above-described weather resistance test (irradiation time: 300 hours). The tensile strength after the weather resistance test is, for example, larger than 40 N / 15 mm, preferably 45 N / 15 mm or more, and more preferably 80 N / 15 mm or more. In addition, about the measurement conditions of tensile strength, it mentions in full detail in the Example mentioned later.

The tear strength by the Elmendorf tearing method of the agricultural sheet is, for example, 1.4N or more, and may be 2.5N or more. On the other hand, the tear strength is, for example, 15N or less, and may be 10N or less.

The agricultural sheet may or may not have a light reflecting layer. When providing a light reflection layer, visible light reflectance can be made higher, and coloring of fruit can be accelerated | stimulated or the raise of ground temperature can be suppressed. The light reflecting layer contains, for example, a white powder and a resin component. Examples of the white powder include anatase type or rutile type titanium oxide, titanium oxide whose surface is treated with a metal oxide such as Al, Si, calcium carbonate, barium sulfate, and the like. Examples of the resin component include polyurethane resins and polyester resins. Examples of the polyurethane resin include polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, and polycaprolactam polyurethane. The location of the light reflecting layer is not particularly limited, and may be the outermost surface of the agricultural sheet or may be inside. Moreover, it is preferable that the light reflection layer is provided on the side opposite to the reinforcing sheet with respect to the base sheet. The thickness of the light reflecting layer is, for example, not less than 0.5 μm and not more than 4 μm.

It is preferable that the agricultural sheet has a high ultraviolet reflectance. This is because it can exert a pest repellent effect. The average reflectance of ultraviolet rays (wavelength of 300 nm or more and 380 nm or less) on the surface of the agricultural sheet on the reinforcing sheet side is, for example, preferably 35% or more, more preferably 60% or more, and 80% or more. Is more preferable. In addition, the “surface on the reinforcing sheet side of the agricultural sheet” refers to a surface on the side opposite to the base sheet side with respect to the reinforcing sheet.

The agricultural sheet may have a plurality of through holes penetrating from one surface to the other surface. The rate of the through holes is, for example, 10,000 pieces / m ² or more and 1,000,000 pieces / m ² , and preferably 100,000 pieces / m ² or more and 700,000 pieces / m ² or less.

The thickness of the agricultural sheet is not particularly limited, but is, for example, 50 μm or more, and may be 80 μm or more. On the other hand, the thickness of an agricultural sheet is 200 micrometers or less, for example, and may be 150 micrometers or less.

5). Agricultural sheet manufacturing method The agricultural sheet manufacturing method is not particularly limited as long as the target agricultural sheet is obtained. For example, a method of laminating a base sheet and a reinforcing sheet via an adhesive layer, a base The method of heat-sealing a sheet | seat and a reinforcement sheet is mentioned.

FIG. 4 is a schematic cross-sectional view showing an example of a method for producing an agricultural sheet. In FIG. 4, an adhesive composition 3x containing an adhesive and a solvent is applied to one surface side of the base sheet 1. (FIG. 4A). Next, the solvent is removed by drying the adhesive composition 3x to form the adhesive layer 3 (FIG. 4B). Next, the base material sheet 1 and the reinforcing sheet 2 are laminated via the adhesive layer 3 (FIG. 4C). Thereby, the agricultural sheet 10 which has the base material sheet 1, the contact bonding layer 3, and the reinforcement sheet 2 in this order is obtained (FIG.4 (d)).

The adhesive composition contains at least an adhesive and a solvent. The adhesive is as described above. On the other hand, examples of the solvent include alcohols such as isopropyl alcohol and normal propyl alcohol, esters such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, and ethylene glycol acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. , Ethers such as diethylene glycol methyl ether, tetrahydrofuran and dioxane, aromatics such as toluene and xylene, and halogenated hydrocarbons.

Examples of the coating method of the adhesive composition include general coating methods such as roll coating, gravure coating, kiss coating, knife coating, dip coating, and spray coating. The temperature for drying the adhesive composition varies depending on the type of the base sheet and the solvent, but is, for example, 90 ° C. or less, and preferably 70 ° C. or less. Further, vacuum drying such as vacuum drying may be performed. The drying time is appropriately selected according to the type of adhesive.

For example, when the base sheet and the reinforcing sheet are pasted together by Roll to Roll, it is preferable to control the pressure by tension. In this case, it is preferable to manage the base sheet for the first paper feed at, for example, 50N to 110N, and more preferably 80N to 100N. In order to prevent curling of the entire sheet, for example, the second reinforcing sheet is preferably managed from 20N to 50N, and more preferably from 30N to 40N. In the dry laminating method, lamination is usually performed in a temperature environment in which the base sheet is not thermally deformed. In addition, although it is not necessary to heat at the time of lamination | stacking, you may heat as long as the base material sheet is the temperature which does not heat-deform.

Note that the present disclosure is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present disclosure has substantially the same configuration and exhibits the same function and effect in any case. It is included in the technical scope of the disclosure.

[Example 1]
(Preparation of base sheet)
Linear low density polyethylene (L-LDPE, melting point 125 ° C., MFR (190 ° C., 2160 g): 2.0 g / 10 min) 100 parts by mass as a polyethylene resin, 2 (2′-hydroxy-5 ′) as an ultraviolet absorber -Tert-octylphenyl) benzotriazole 0.1 parts by mass, NOR-type hindered amine light stabilizer (manufactured by Adeka, Adekastab LA-81, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidine- 4-yl) carbonate) 0.4 parts by mass, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propinate] 0.1 parts by mass as a phenolic antioxidant, inorganic filling Calcium carbonate as agent 1 (heavy calcium carbonate (PE masterbatch with 60% filling rate): PE 20 parts by mass) 20 parts by mass, 40 parts by mass of a titanium pigment (PE master batch with a filling rate of 80%: PE content 8 parts by mass) as the inorganic filler 2 are mixed at 180 ° C. using a Banbury mixer. Was melt kneaded.

In addition, the total amount of the polyethylene resin contained in the obtained kneaded material is 116 parts by mass, and the content of the NOR type hindered amine light stabilizer with respect to the polyethylene resin is 0.34% by mass. Moreover, content of the inorganic fillers 1 and 2 with respect to a polyethylene-type resin is 51.7 mass%.

Next, the obtained kneaded material is supplied to a 12 inch diameter × 30 L common head type mixing roll (rotational speed: 18 rpm), rolled at a roll temperature of 165 ° C. or more and 190 ° C. or less, and a substrate sheet having a thickness of 30 μm. (Polyethylene sheet) was obtained.

(Production of agricultural sheet)
An L-LDPE film (linear low density polyethylene film, 30 μm thick, TUX TC-S, manufactured by Mitsui Chemicals, Inc.) is prepared as a reinforcing sheet, and the reinforcing sheet and the base sheet are joined by the dry laminating method. did. Specifically, Takelac A-969V (polyol component) and Takenate A-5 (isocyanate component) were used as polyether adhesives. The polyether-based adhesive was applied and bonded under the conditions of a drying temperature of 70 ° C. and 2 g / m ² . In this way, an agricultural sheet was obtained.

[Example 2]
An agricultural sheet was obtained in the same manner as in Example 1 except that the amount of the hindered amine light stabilizer was 0.1 parts by mass (0.086% by mass relative to the polyethylene resin).

[Example 3]
An agricultural sheet was obtained in the same manner as in Example 1 except that the amount of the hindered amine light stabilizer was 0.7 parts by mass (0.603% by mass relative to the polyethylene resin).

[Example 4]
An agricultural sheet was obtained in the same manner as in Example 1 except that the amount of the hindered amine light stabilizer was 5.8 parts by mass (0.500% by mass relative to the polyethylene resin).

[Example 5]
An agricultural sheet was obtained in the same manner as in Example 1 except that the amount of the hindered amine light stabilizer was 10.5 parts by mass (9.051% by mass relative to the polyethylene resin).

[Example 6]
An agricultural sheet was obtained in the same manner as in Example 1 except that high-density polyethylene (HDPE, melting point 130 ° C., MFR (190 ° C., 2160 g): 0.5 g / 10 min) was used as the polyethylene resin.

[Comparative Example 1]
Hindered amine light stabilizers from Adeka Stab LA-81 to non-NOR hindered amine light stabilizers (Adekastab LA-68, manufactured by Adeka, 1,2,3,4-Butanetetracarboxylic acid, tetramethyl ester, reaction products with 2 , 2,6,6-tetramethyl-4-piperidinol and β, β, β ', β'-tetramethyl-2,4,8,10-tetra oxaspiro [5.5] undecane-3,9-diethanol) Except for the above, an agricultural sheet was obtained in the same manner as in Example 1.

[Comparative Example 2]
An agricultural sheet was obtained in the same manner as in Example 1 except that the hindered amine light stabilizer was not blended.

[Evaluation]
(Weather resistance test)
A weather resistance test was performed on the agricultural sheets obtained in Examples 1 to 6 and Comparative Examples 1 and 2. In the weather resistance test, the obtained agricultural sheet was cut into 5 cm × 5 cm to prepare a sample. This sample was immersed in sulfite water (sulfurous acid 5 mass%, pH 1.5) for 72 hours, and a weather resistance test was conducted by a metal halide lamp type weather resistance test (equipment standard: JTMG-01: 2000, Japan Testing Machine Industry Association). (Irradiance 90 mW / cm ² or more and 100 mW / cm ² or less, maximum irradiation time 300 hours). The results are shown in Table 1. The case where there was no appearance abnormality such as discoloration and cracking was evaluated as “good”, and the case where there was an appearance abnormality such as cracking was rated as “x”.

(Visible light average reflectance measurement)
The average reflectance measurement of visible light was performed on the agricultural sheets before and after the weather resistance test. For the measurement of the average reflectance of visible light, using an ultraviolet / visible / near-infrared spectrophotometer (Shimadzu UV-3600) and an integrating sphere attachment (ISR-3100), an incident angle of 8 ° and a visible region wavelength of 380 nm or more. The reflectance (total reflectance) at 780 nm or less was measured, and the average reflectance was obtained. As a standard plate, Spectralon (manufactured by Teflon (registered trademark)) manufactured by Labsphere, USA was used. The measurement surface was the surface on the base sheet side of the agricultural sheet. The results are shown in Table 1.

(Tensile strength measurement)
Tensile strength measurement was performed on the agricultural sheet after the weather resistance test. In the tensile strength measurement, in accordance with JIS K7127 and JIS K7161, a precision universal testing machine ("Autograph AG-500N" manufactured by Shimadzu Corporation) is used, and the flow direction (MD direction), sample width 15 mm, distance between gauge points 15 mm The measurement was performed under the conditions of a tensile speed of 200 mm / min. The results are shown in Table 1. In Table 1, “after the weather resistance test” means that 300 hours have elapsed since the start of the weather resistance test.

As shown in Table 1, in Examples 1 to 6, the results of the weather resistance test (50 hours, 100 hours, 200 hours, 300 hours) were all good. On the other hand, although the comparative example 1 had better weather resistance than the comparative example 2 which did not use the light stabilizer, the appearance abnormality occurred after 50 hours. The average visible light reflectance of the agricultural sheets obtained in Examples 1 to 6 and Comparative Examples 1 and 2 was as high as 84% or more even after the weather resistance test.

[Example 7]
First, similarly to Example 1, a base sheet and a reinforcing sheet were prepared. Next, an anchor coating agent layer having a thickness of 0.5 g / m ² (in a dry state) was formed by coating a urethane anchor coating agent on the base sheet. Further, while the linear low density polyethylene (LLDPE, MI = 8.0, density = 0.911) is melt-extruded on the anchor coating agent layer, the thickness of the melt-extruded resin surface is subjected to ozone treatment. Extrusion coating was performed at 15 μm, and the laminate was laminated with a reinforcing sheet to obtain an agricultural sheet. The molten resin temperature of LLDPE was 260 ° C.

[Evaluation]
A punching test was performed on the agricultural sheet obtained in Example 7, and it was evaluated whether it could be applied to two-strand rolling. Specifically, as shown in FIGS. 5 and 6, a circular opening 11 was formed by pressing a multi-cutter 30 including a cylindrical punching portion 31 against the agricultural sheet 10 covering the soil 20. . In addition, the width W of the adjacent opening part 11 was 40 cm, and the diameter of the opening part 11 was 10 cm. As a result, the agricultural sheet obtained in Example 7 had no tear at the end of the opening. The agricultural sheet obtained in Example 7 uses a base sheet (polyethylene sheet) and a reinforcing sheet containing a polyethylene resin, which is considered to be because of high flexibility. That is, it can be set as the agricultural sheet | seat excellent in workability by combining a base material sheet (polyethylene sheet) and the reinforcement sheet containing a polyethylene-type resin. It turned out that the said agricultural sheet | seat is suitable for the mulch for two-row cultivation called 2 row sowing.

[Example 8]
A kneaded material was obtained in the same manner as in Example 1 except that high-density polyethylene (HDPE, melting point 130 ° C., MFR (190 ° C., 2160 g): 0.5 g / 10 min) was used as the polyethylene resin. A base sheet (polyethylene sheet) was obtained in the same manner as in Example 1 except that the obtained kneaded material was used and the thickness was changed to 60 μm. This was an agricultural sheet.

[Example 9]
An agricultural sheet was obtained in the same manner as in Example 8 except that a reinforcing sheet was provided on one side of the base sheet. Specifically, a polyethylene mesh cloth made of polyethylene resin (thickness 55 μm, driving strength 6 × 5 / inch) is prepared as a reinforcing sheet, and a urethane anchor coating agent is coated on the base sheet. Thus, an anchor coating agent layer having a thickness of 0.5 g / m ² (dry state) was formed. Further, on the anchor coating agent layer, low density polyethylene (LDPE, MI = 8.0, density = 0.92) was extrusion coated at a thickness of 15 μm while being subjected to ozone treatment, and bonded to the reinforcing sheet. Agricultural sheet was obtained. The molten resin temperature of LDPE was 260 ° C.

[Example 10]
An agricultural sheet was obtained in the same manner as in Example 9 except that a polyethylene mesh cloth (thickness 55 μm, driving strength 8 × 8 / inch) made of polyethylene resin was used as the reinforcing sheet.

[Example 11]
An agricultural sheet was obtained in the same manner as in Example 9 except that a polyethylene mesh cloth (thickness 55 μm, driving strength 5 × 5 / inch) made of polyethylene resin was used as the reinforcing sheet.

[Comparative Example 3]
An agricultural sheet was obtained in the same manner as in Example 8, except that the hindered amine light stabilizer was changed from Adeka Stab LA-81 to a hindered amine light stabilizer that is not NOR type (Adeka Stub LA-68, manufactured by Adeka). It was.

[Evaluation]
The agricultural sheet obtained in Examples 8 to 11 and Comparative Example 3 was subjected to a weather resistance test, a visible light average reflectance measurement, and a tensile strength measurement. Test conditions and measurement conditions are the same as those described above. The results are shown in Table 2. “After the weather resistance test” in Table 2 means that 300 hours have elapsed since the start of the weather resistance test.

(Spelling needle holding strength measurement)
The strength (spelling needle holding strength) in JIS A6930 was measured for the agricultural sheet after the weather resistance test. In the spelling needle holding strength measurement, the agricultural sheet after the weather resistance test was cut into 5 cm × 5 cm and used as samples. This sample was measured using a precision universal testing machine (“Autograph AG-500N” manufactured by Shimadzu Corporation) at a distance between gauge points of 100 mm, 180 ° peeling, a tensile speed of 200 mm / min, and a temperature of 23 ° C. The results are shown in Table 2.

(Measurement of elongation at break)
Tensile elongation was measured on the agricultural sheets before and after the weather resistance test. In tensile elongation measurement, in accordance with JIS K7127, using a precision universal testing machine ("Autograph AG-500N" manufactured by Shimadzu Corporation), the conditions of flow direction (MD direction), sample width of 15 mm, and speed of 200 mm / min. And was calculated from the length when the sample was broken.
Elongation at break (%) = (L−Lo) / Lo × 100
Lo: sample length before the test, L: sample length at break The results are shown in Table 3.

As shown in Table 2, in Examples 8 to 11, the results of the weather resistance test (50 hours, 100 hours, 200 hours, 300 hours) were all good. On the other hand, since the hindered amine light stabilizer which is not NOR type was used for the comparative example 3, the appearance abnormality occurred after 100 hours. In addition, the average visible light reflectance of the agricultural sheets (agricultural sheets before the light resistance test) obtained in Examples 8 to 11 and Comparative Example 3 was as high as 92.0% or more. Furthermore, when the visible light average reflectance after the weather resistance test of the agricultural sheet obtained in Example 8 and Comparative Example 3 was compared, the weather resistance test was performed in Example 8 using a hindered amine light stabilizer that is a NOR type. Although the fall of the visible light average reflectance after that was able to be suppressed, in the comparative example 3 using the hindered amine light stabilizer which is not NOR type, the visible light average reflectance after a weather resistance test fell slightly. Furthermore, the agricultural sheets obtained in Examples 8 to 11 all had higher tensile strength than the agricultural sheet obtained in Comparative Example 3. Particularly in Examples 9 to 10 in which the reinforcing sheet was provided, the effect was remarkable. Moreover, when the spelling needle holding strength of the agricultural sheet obtained in Example 8 and Comparative Example 3 was compared, compared with Comparative Example 3 using a hindered amine light stabilizer that is not a NOR type, a hindered amine that is a NOR type. In Example 8 using the system light stabilizer, better spelling needle holding strength was obtained.

As shown in Table 3, in Example 8, even when the irradiation time was 300 hours, a high maintenance ratio (E ₃₀₀ / E ₀ ) could be obtained. In contrast, in Comparative Example 3, when the irradiation time was 50 hours, the breaking elongation was already reduced to 1/10. Thus, when the base sheet contains a polyethylene resin (especially HDPE), the degradation of the breaking elongation could be remarkably suppressed by using the NOR type hindered amine light stabilizer. Moreover, since deterioration of breaking elongation can be suppressed, there exists an advantage that it is hard to break even if an agricultural sheet is stepped on, for example.

[Example 12]
(Preparation of base sheet)
As a resin composition constituting the inner layer of the base sheet, a propylene homopolymer (manufactured by Nippon Polychem Co., Ltd., trade name “Novatech PP: MA-8”, melting point 164 ° C.) is 65.5% by mass, high density polyethylene Calcium carbonate powder (made by Nippon Polychem Co., Ltd., trade name “NOVATEC HD: HJ580”, melting point 134 ° C., density 0.960 g / cm ³ ) of 6.5% by mass and an average particle size of 1.5 μm An unstretched sheet was obtained from the resin composition comprising 28% by mass using an extruder. Next, this unstretched sheet was stretched 4 times in the longitudinal direction to obtain a uniaxially stretched sheet.

On the other hand, as a resin composition constituting the outer layer of the base sheet, a propylene homopolymer of 51.5% by mass, high density polyethylene of 3.5% by mass, and an average particle size of 1. A resin composition comprising 42% by mass of 5 μm calcium carbonate powder and 3% by mass of titanium oxide powder having an average particle diameter of 0.8 μm was prepared. 0.1 parts by mass of 2 (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, NOR-type hindered amine light stabilizer (manufactured by Adeka, Adekastab LA-81, bis (1-undecanoxy-2,2) , 6,6-tetramethylpiperidin-4-yl) carbonate) 0.3 parts by mass, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] 0.1 part by mass, melt kneaded using another extruder, extruded from both dies on the surface of the uniaxially stretched sheet, A laminated sheet having an outer layer, an inner layer, and an outer layer was obtained.

Next, this laminated sheet is stretched by 7 times in the transverse direction and slits at the ears, so that the thickness is 70 μm, the outer layer (15 μm), the inner layer (40 μm), and the outer layer (15 μm) have a layer structure and are fine A base material sheet (porous polypropylene sheet) containing various voids was obtained.

(Production of agricultural sheet)
An agricultural sheet was obtained in the same manner as in Example 1 except that the obtained base sheet was used.
[Example 13]
Example 12 except that 0.1 part by mass of heavy metal deactivator (ADEKA CDA-1, Adeka, 2-Hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide) was blended. An agricultural sheet was obtained in the same manner.

[Comparative Example 4]
The hindered amine light stabilizer in Example 12 was changed from Adekastab LA-81 to a hindered amine light stabilizer that is not NOR type (Adekastab LA-57, manufactured by Adeka, 2,2,6,6-tetramethyl-4-piperidylbutane- An agricultural sheet was obtained in the same manner as in Example 12 except that the composition was changed to 1,2,3,4-tetracarboxylate).

[Example 14]
First, similarly to Example 1, a base sheet and a reinforcing sheet were prepared. Next, a urethane-based anchor coating agent was coated on the base sheet to form an anchor coating agent layer having a thickness of 0.5 g / m ² (dry state). Further, a low-density polyethylene (LDPE, MI = 8.0, density = 0.92) is melt-extruded (extrusion coating) at a thickness of 15 μm while being subjected to ozone treatment on the anchor coating agent layer, and a reinforcing sheet And the agricultural sheet was obtained. The molten resin temperature of LDPE was 260 ° C.

[Example 15]
(Preparation of base sheet)
A kneaded material was obtained in the same manner as in Example 1 except that high-density polyethylene (HDPE, melting point 130 ° C., MFR (190 ° C., 2160 g): 0.5 g / 10 min) was used as the polyethylene resin. A base sheet (polyethylene sheet) was obtained in the same manner as in Example 1 except that the obtained kneaded material was used and the thickness was changed to 60 μm.

(Production of agricultural sheet)
As a reinforcing sheet, a polyethylene mesh cloth (thickness: 65 μm) made of polyethylene resin was prepared. Next, a urethane-based anchor coating agent was coated on the base sheet to form an anchor coating agent layer having a thickness of 0.5 g / m ² (dry state). Further, a low-density polyethylene (LDPE, MI = 8.0, density = 0.92) is melt-extruded (extrusion coating) at a thickness of 15 μm while being subjected to ozone treatment on the anchor coating agent layer, and a reinforcing sheet And the agricultural sheet was obtained.

[Comparative Example 5]
Except that the hindered amine light stabilizer in Example 15 was changed from Adeka Stab LA-81 to a hindered amine light stabilizer other than the NOR type (Adeka Stub LA-57, manufactured by Adeka), the same as in Example 15. Agricultural sheet was obtained.

[Evaluation]
(Weather resistance test)
A weather resistance test was performed on the agricultural sheets obtained in Examples 1 and 12 to 15 and Comparative Examples 4 and 5. The conditions for the weather resistance test are the same as those described above, except that the irradiation time is changed to 100 hours. Moreover, about Example 12, the weather resistance test was similarly done using the diluted hydrochloric acid aqueous solution (pH1.0) instead of the sulfurous acid aqueous solution.

After the test, the number average molecular weight (Mn) of the polyolefin resin contained in the base sheet was measured. For the measurement, a high temperature GPC apparatus (Senshu Scientific SSC-7120 HT-GPC System) was used. As a pretreatment, the base sheet (test piece) was left in o-dichlorobenzene at 145 ° C. for 1 hour and then stirred for 1 hour to dissolve, and membrane filters with filter pore sizes of 0.5 μm and 1.0 μm were prepared. And pressure filtered. The measurement conditions are as follows.
Sample: About 3 mg of test piece for 3 mL of solvent Injection volume: 300 μL
Guard column: HT-G
Column: 2 HT-806M Column temperature: 145 ° C
Mobile phase: o-dichlorobenzene (containing 0.025 mass% BHT)
Flow rate: 1.0 mL / min
Detector: Differential refractometer Molecular weight calibration: Polystyrene conversion Table 4 shows the results of number average molecular weight obtained by GPC measurement. In Table 4, “after the weather resistance test” means 100 hours after the start of the weather resistance test.

(Copper damage assessment)
Copper damage evaluation was performed on the agricultural sheets obtained in Example 13 and Comparative Example 4 before acid immersion. In copper damage evaluation, the agricultural sheet | seat was closely_contact | adhered to 5 cm square copper foil, both sides were pinched | interposed with 4 mm quartz glass, glass was fixed with the polyimide tape, and the sample was obtained. The obtained sample was allowed to stand in an oven at 120 ° C. for 100 hours. Then, the agricultural sheet | seat was confirmed, the case where there was no appearance abnormality was evaluated as (circle), and the case where decomposition | disassembly had produced was evaluated as x. The results are shown in Table 4. The copper damage evaluation corresponds to a resistance of 40 ° C. × 3 years.

(Visible light average reflectance measurement)
The agricultural sheet obtained in Examples 1 and 12 to 15 and Comparative Examples 4 and 5 was subjected to visible light average reflectance measurement before acid immersion. The measurement conditions are the same as those described above. The results are shown in Table 4.

As shown in Table 4, in Examples 1 and 12 to 15, the polyolefin resin after the weather resistance test was able to maintain a high number average molecular weight. On the other hand, in Comparative Examples 4 and 5, the number average molecular weight value and the maintenance rate after the weather resistance test were low. Moreover, about copper damage evaluation, although the external appearance abnormality did not generate | occur | produce in Example 13, the partial decomposition | disassembly of the agricultural sheet | seat was confirmed in the comparative example 4. FIG. Further, the agricultural sheets obtained in Examples 1 and 12 to 15 and Comparative Examples 4 and 5 all had high visible light average reflectance.

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Reinforcement sheet 3, 4 ... Adhesive layer 10 ... Agricultural sheet 20 ... Soil 30 ... Multi cutter

Claims (17)

1. Having a base sheet containing a polyolefin-based resin, a light stabilizer and an inorganic filler;
   The inorganic filler contains at least one of calcium carbonate and titanium oxide;
   An agricultural sheet, wherein the light stabilizer includes a NOR-type hindered amine light stabilizer.
2. The agricultural sheet according to claim 1, wherein an average reflectance of visible light (wavelength of 380 nm or more and 780 nm or less) is 90% or more.
3. The agricultural sheet according to claim 1, wherein the content of the inorganic filler in the base sheet is 50% by mass or more based on the polyolefin resin.
4. The substrate sheet was immersed in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, and then a metal halide lamp type weather resistance test was performed under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 300 hours. In this case, the agricultural sheet according to claim 1, wherein the base sheet has a tensile strength of 10 N / 15 mm or more.
5. The substrate sheet was immersed in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, and then a metal halide lamp type weather resistance test was performed under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 300 hours. In this case, the agricultural sheet according to claim 1, wherein a spelling needle holding strength of the base material sheet is 10 N or more.
6. The substrate sheet was immersed in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, and then a metal halide lamp type weather resistance test was performed under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 300 hours. In this case, the agricultural sheet according to claim 1, wherein the elongation at break of the base sheet is 300% or more.
7. After immersing the base sheet in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, a metal halide lamp type weather resistance test was performed under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 300 hours, When the elongation at break of the base sheet before being immersed in the aqueous sulfurous acid solution is E ₀ (%), and the elongation at break of the base sheet after the metal halide lamp type weather resistance test is E ₃₀₀ (%) _, the value of _E 300 / _{E 0} is 0.50 or more, agricultural sheet according to claim 1.
8. The agricultural sheet according to claim 7, wherein the _E300 is 300% or more.
9. The substrate sheet was immersed in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, and then a metal halide lamp type weather resistance test was performed under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 100 hours. In this case, the agricultural sheet according to claim 1, wherein the polyolefin resin has a number average molecular weight of 30,000 or more.
10. After immersing the base sheet in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, a metal halide lamp type weather resistance test was performed under the conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 100 hours, When the number average molecular weight of the polyolefin resin before dipping in the aqueous sulfurous acid solution is M ₀ and the number average molecular weight of the polyolefin resin after the metal halide lamp type weather resistance test is M ₁₀₀ , M ₁₀₀ / M The agricultural sheet | seat of Claim 1 whose value of ₀ is 0.70 or more.
11. After immersing the base sheet in an aqueous sulfurous acid solution having a concentration of 5% by mass for 72 hours, a metal halide lamp type weather resistance test was performed under the conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 100 hours, When the number average molecular weight of the polyolefin resin before dipping in the aqueous sulfurous acid solution is M ₀ and the number average molecular weight of the polyolefin resin after the metal halide lamp type weather resistance test is M ₁₀₀ , M ₁₀₀ / M The agricultural sheet according to claim 1, wherein the value of ₀ is 0.60 or more, and the M ₁₀₀ is 20,000 or more.
12. The agricultural sheet according to claim 1, wherein the base sheet contains a heavy metal deactivator.
13. The agricultural sheet according to claim 1, wherein the agricultural sheet has a reinforcing sheet on one surface side of the base sheet.
14. When the agricultural sheet is immersed in an aqueous sulfite solution having a concentration of 5% by mass for 72 hours and then subjected to a metal halide lamp type weather resistance test under conditions of an irradiance of 90 mW / cm ^{2 to} 100 mW / cm ² and an irradiation time of 300 hours. The agricultural sheet according to claim 13, wherein the agricultural sheet has a tensile strength greater than 40 N / 15 mm.
15. The agricultural sheet according to claim 14, wherein the agricultural sheet has a tensile strength of 80 N / 15 mm or more.
16. The reinforcing sheet has a cross type nonwoven fabric having 5 or more fibers along the first direction and 5 or more fibers along the second direction intersecting the first direction in a 1 inch square area. The agricultural sheet according to claim 13, wherein
17. The base sheet contains a polyethylene resin as the polyolefin resin,
    The agricultural sheet according to claim 13, wherein the reinforcing sheet contains a polyethylene resin.

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