JP7005938B2 - Agricultural sheet - Google Patents

Description

This disclosure relates to agricultural sheets.

The agricultural sheet is used, for example, as a member for covering soil or agricultural products, a member for an agricultural house, or the like. Agricultural sheets imparted with light reflectivity can be used, for example, for solving light shortages in houses, promoting coloring of harvested products, controlling soil temperature, and controlling weeds.

Patent Document 1 describes an agricultural sheet provided with a sheet base material and a light reflecting 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. It is a porous thermoplastic resin sheet having voids in the range of, having a porosity in the range of 35% to 60%, and having a thickness in the range of 30 μm to 90 μm, and further, the light reflecting layer thereof. Agricultural sheets with a thickness in the range of 0.5 μm to 4 μm are disclosed.

Japanese Unexamined Patent Publication No. 2014-233206

When the agricultural sheet is used as a member for covering soil or crops, as a method of fixing the agricultural sheet, for example, as shown in FIG. 4, a method of piercing the pin 20 into the agricultural sheet 10 and fixing the agricultural sheet to the soil can be mentioned. However, when a pin is pierced into the agricultural sheet, the agricultural sheet may be torn from the hole formed through the pin. Such damage to the agricultural sheet becomes remarkable when the agricultural sheet is used outdoors because the agricultural sheet is blown by the wind. Therefore, there is a demand for agricultural sheets with good durability.

By the way, by imparting desired light reflectivity to the agricultural sheet, it is possible to use the agricultural sheet for purposes such as solving a shortage of light rays in a house, promoting coloring of harvested products, suppressing soil temperature, and controlling weeds. It becomes. The light reflectivity of the agricultural sheet can be imparted, for example, by containing an inorganic filler in the polyolefin sheet. Here, the light reflectivity of the agricultural sheet can be controlled by the content of the inorganic filler contained in the polyolefin sheet, and the more the content of the inorganic filler is increased, the higher the light reflectivity can be. However, if the content of the inorganic filler contained in the polyolefin sheet is too high, the durability of the agricultural sheet tends to decrease. Therefore, there is a problem that it is difficult to obtain desired light reflectivity while maintaining durability in an agricultural sheet.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide an agricultural sheet capable of achieving both durability and light reflection of the agricultural sheet.

In the present disclosure, a polyolefin sheet containing a polyolefin resin and an inorganic filler and a reinforcing sheet are provided, the thickness of the polyolefin sheet is 150 μm or less, and the strength (spelling needle holding strength) in JIS A6930 is high. Provide agricultural sheets with 35N or more.

The agricultural sheet of the present disclosure has the effect of being able to achieve both durability and light reflectivity.

It is a schematic sectional drawing which shows an example of the agricultural sheet of this disclosure. It is a schematic sectional drawing which shows the other example of the agricultural sheet of this disclosure. It is a schematic process diagram which shows an example of the manufacturing method of the agricultural sheet of this disclosure. It is explanatory drawing for demonstrating the agricultural sheet of this disclosure.

Hereinafter, the agricultural sheet of the present disclosure will be described in detail.

FIG. 1 is a schematic cross-sectional view showing an example of the agricultural sheet of the present disclosure. The agricultural sheet 10 in FIG. 1 has a polyolefin sheet 1 and a reinforcing sheet 2. Further, the thickness of the polyolefin sheet 1 is 150 μm or less, and the strength (spelling holding strength) in JIS A6930 is 35 N or more. The thickness of the polyolefin sheet is, for example, the distance indicated by the reference numeral t in FIG.

The light reflectivity of the agricultural sheet can be imparted, for example, by containing an inorganic filler in the polyolefin sheet. Here, the light reflectivity of the agricultural sheet can be controlled by the content of the inorganic filler contained in the polyolefin sheet, and the more the content of the inorganic filler is increased, the higher the light reflectivity can be. On the other hand, if the content of the inorganic filler contained in the polyolefin sheet increases too much, the durability of the agricultural sheet tends to decrease. Therefore, there is a problem that it is difficult to obtain desired light reflectivity while maintaining durability in an agricultural sheet. The durability referred to here means, for example, as shown in FIG. 4, when the pin 20 is pierced and fixed to the agricultural sheet 10, the agricultural sheet is torn from the hole formed through the pin. Refers to the property of being able to suppress. Further, the durability of the agricultural sheet referred to in the present disclosure can be evaluated by the strength (holding of the spelling needle) in JIS A6930.

According to the present disclosure, by providing a reinforcing sheet on the polyolefin sheet and setting the strength (spelling needle holding strength) in JIS A6930 to 35 N or more, both durability and light reflectivity can be achieved at the same time.

Here, the strength (spelling needle holding strength) of the agricultural sheet in JIS A6930 in the present disclosure is the strength around the hole formed through the spelling needle when the spelling needle is pierced into the agricultural sheet. For example, the measurement can be performed under the conditions that the thickness of the polyolefin sheet is 150 μm or less and the temperature is 23 ° C. Further, in the present disclosure, "strength in JIS A6930 (spelling needle holding strength) of 35 N or more" means strength in JIS A6930 (spelling needle holding strength) in both the longitudinal direction and the width direction of the agricultural sheet. Indicates that is 35N or more.

Further, in the present disclosure, the strength (spelling needle holding strength) of the agricultural sheet in JIS A6930 may be 35 N or more. In the present disclosure, it is particularly preferable that the strength (spelling needle holding strength) of the agricultural sheet in JIS A6930 is 40 N or more when the thickness of the polyolefin sheet is 150 μm or less.

Hereinafter, the agricultural sheet of the present disclosure will be described for each configuration.

1. 1. Polyolefin Sheet The polyolefin sheet in the present disclosure is a white sheet containing a polyolefin resin and an inorganic filler, and exhibits light reflectivity. The polyolefin sheet may have a single-layer structure or a multi-layer structure. When the polyolefin sheet has a multi-layer structure, the resin components contained in each layer may be the same or different. As an example of the polyolefin sheet having a multi-layer structure, it has an inner layer and two outer layers located on both sides of the inner layer, and the resin components contained in the two outer layers are the same, and the resin component contained in the outer layer and the interior are used. Examples thereof include polyolefin sheets having different resin components from those contained in.

The polyolefin sheet may be a non-stretched sheet or a stretched sheet (uniaxially stretched sheet, biaxially stretched sheet, etc.).

The polyolefin sheet may be a sheet having voids inside (porous polyolefin sheet) or a sheet having no voids inside.

The thickness of the polyolefin sheet is, for example, 150 μm or less, 100 μm or less, or 80 μm or less. If the thickness of the polyolefin sheet is too large, the mass of the agricultural sheet may increase and the handleability may decrease. On the other hand, the thickness of the polyolefin sheet is, for example, 25 μm or more, 30 μm or more, or 40 μm or more. If the thickness of the polyolefin sheet is too small, the strength may be low. In addition, since the amount of resin used is large, the manufacturing cost of agricultural sheets is also high.

The polyolefin sheet preferably has a high visible light reflectance. The average reflectance of visible light (wavelength 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 measurement conditions for the average reflectance of visible light will be described in detail in Examples. The total reflectance of the polyolefin sheet at a wavelength of 600 nm is, for example, 70% or more, 80% or more, or 90% or more.

The polyolefin sheet preferably has high smoothness. Specifically, the arithmetic mean height Sa of the surface of the polyolefin sheet is, for example, 1 μm or less, preferably 0.7 μm or less, and more preferably 0.5 μm or less. Further, it is preferable that the polyolefin sheet has high antifouling property. Specifically, the contamination grade (JIS-L-1919) on the surface of the polyolefin sheet is preferably 3 grade or higher.

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

Examples of the polyolefin-based resin include polyethylene-based resin and polypropylene-based resin. Examples of the polyethylene-based resin include high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), and the like. 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 the high-density polyethylene is excellent in weather resistance and tensile strength, and the sheet containing the high-density polyethylene has no slack even in a long roll and is less likely to cause an appearance defect due to whitening during bending.

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, and is 0. It is more preferably .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 calendar processing.

The polyolefin sheet may contain a polyethylene-based resin as the main component of the resin component. The ratio of the polyethylene-based 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-based resin include homopolymerized polypropylene (h-PP), random copolymerized polypropylene (r-PP), block copolymerized polypropylene (b-PP), metallocene polypropylene and the like. These may be used alone or in combination of two or more. Of these, random copolymerized polypropylene is preferred. This is because the random copolymer polypropylene has more flexibility than the homopolymerized polypropylene and the block copolymer polypropylene.

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

The polypropylene 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, and is 0. It is more preferably .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 calendar processing.

The polyolefin sheet may contain a polypropylene-based resin as the main component of the resin component. The ratio of the polypropylene-based 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 polyolefin sheet may contain both a polypropylene-based resin and a polyethylene-based resin as a resin component.

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

(2) Inorganic Filler The polyolefin sheet contains an inorganic filler which is at least one of calcium carbonate and titanium oxide in order to enhance whiteness and light reflectivity. The polyolefin sheet may further contain an inorganic filler such as talc, titanium oxide, titanium oxide, antimony oxide, and a nickel oxide solid solution, if necessary.

The content of the inorganic filler in the polyolefin sheet is, for example, 30 parts by mass or more, 40 parts by mass or more, or 50 parts by mass or more with respect to 100 parts by mass of the polyethylene resin. If the content of the inorganic filler is too low, the whiteness and light reflectivity of the polyolefin sheet may be reduced. On the other hand, the content of the inorganic filler is, for example, 80 parts by mass or less, 75 parts by mass or less, or 70 parts by mass or less with respect to 100 parts by mass of the polyethylene resin. If the content of the inorganic filler is too high, the flexibility of the polyolefin sheet may be reduced.

(3) Light Stabilizer The polyolefin sheet may contain a light stabilizer, if necessary. Examples of the light stabilizer include hindered amine-based light stabilizers, and among them, NOR-type hindered amine light stabilizers are preferable. Agricultural sheets may be exposed to acidic environments such as acid rain, pesticide spraying, and sulfur fumigation, but NOR-type hindered amine-based light stabilizers have good acid resistance and weather resistance is greatly improved.

The NOR-type hindered amine-based light stabilizer is a light stabilizer having excellent acid resistance. As an example of the NOR type hindered amine-based light stabilizer, a compound containing a group represented by the general formula (1) can be mentioned.

In the general formula (1), R is a substituted or unsubstituted hydrocarbon group or 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. Examples thereof include a group, a thioalkoxy group-substituted alkyl group and the like. Note that * and ** in the general formula (1) indicate a state in which they can be combined with other elements.

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

In the general formula (2), R ¹ and R ² are independently substituted or unsubstituted hydrocarbon groups or acyl groups, as in the case of R in the general formula (1) described above. Above all, it is preferable that R ¹ and R ² are each independently an alkyl group having 4 or more carbon atoms and 20 or less carbon atoms.

In the general formula (3), R ³ and R ⁴ are independently substituted or unsubstituted hydrocarbon groups or acyl groups, as in the case of R in the general formula (1) described above. Above all, it is preferable that R ³ and R ⁴ are each independently an alkyl group having 4 or more and 20 or less carbon atoms. Further, R5 is an alkylene group having ¹ or more carbon atoms and 8 or less carbon atoms.

Specific examples of the NOR-type hindered amine-based light stabilizer include Adeka Stub LA-81 manufactured by Adeka Corporation and Tinubin 123 manufactured by BASF (bis (2,2,6,6-tetramethyl-1- (octyloxy)). ) -4-piperidinyl) ester) and the like.

The content of the light stabilizer in the polyolefin sheet is, for example, 0.05 parts by mass or more, may be 0.1 parts by mass or more, or 0.15 parts by mass or more with respect to 100 parts by mass of the polyolefin resin. There may be. If the content of the light stabilizer is too low, the weather resistance of the polyolefin sheet may not be improved. On the other hand, the content of the light stabilizer in the polyolefin sheet is, for example, 10.0 parts by mass or less, may be 9.0 parts by mass or less, or 8.0 parts by mass with respect to 100 parts by mass of the polyolefin resin. It may be as follows. If the content of the light stabilizer is too high, the manufacturing cost may increase.

(4) Additives The polyolefin sheet may contain at least one of an antioxidant and an ultraviolet absorber. Since it is presumed that the deterioration of the antioxidant and the ultraviolet absorber is caused by the reaction with the protons in the acidic solution, the antioxidant and the ultraviolet absorber are preferably materials having high acid resistance.

(A) Antioxidants Examples of the antioxidants include phenolic antioxidants and phosphorus-based antioxidants. Examples of the phenolic antioxidant include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propinate], 2,6-di-t-butyl-4-methylphenol, and the like. 4,4'-Methylene-bis (2,6-di-t-butyl) phenol, 4,4'-butylidene-bis (6-t-butyl-3-methyl) phenol, 2,2-methylene-bis (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) Examples thereof include 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, examples of the phosphorus-based antioxidant include trisnonylphenyl phosphite, tris (2,4-dithiary butylphenyl) phosphite, and tris [2-third butyl-4- (3-third butyl-). 4-Hydroxy-5-methylphenylthio) -5-methylphenyl] phosphite, tridecylphosphite, octyldiphenylphosphite, di (decyl) monophenylphosphite, di (tridecyl) pentaerythritol diphosphite, distearyl Pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, bis (2,4-ditertiary butylphenyl) pentaerythritol diphosphite, bis (2,6-ditertiary butyl-4-methylphenyl) ) Pentaerythritol diphosphite, bis (2,4,6-tritrithbutylphenyl) pentaerythritol diphosphite, tetra (tridecyl) isopropylidene diphenol diphosphite, tetra (tridecyl) -4,4'-n -Butylidenebis (2-tertiary butyl-5-methylphenol) diphosphite, hexa (tridecyl) -1,1,3-tris (2-methyl-4-hydroxy-5-third butylphenyl) butanetriphosphite, tetrakis ( 2,4-Ditertiary Butylphenyl) Biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tris (2-[(2,4,8,10) -Tetrakiss tertiary butyldibenzo [d, f] [1,3,2] dioxaphosphepine-6-yl) oxy] ethyl) amine and the like can be mentioned.

The content of the antioxidant in the polyolefin sheet is, for example, 0.05 parts by mass or more, may be 0.1 parts by mass or more, or 0.4 parts by mass or more with respect to 100 parts by mass of the polyolefin resin. There may be. If the content of the antioxidant is too low, the weather resistance of the polyolefin sheet may not be improved. On the other hand, the content of the antioxidant in the polyolefin sheet is, for example, 5.0 parts by mass or less, may be 3.0 parts by mass or less, or 1.0 part by mass with respect to 100 parts by mass of the polyolefin resin. It may be as follows. Too much antioxidant content can lead to poor appearance due to bleed-out.

(B) Ultraviolet absorbers Examples of the ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Further, as the benzotriazole-based ultraviolet absorber, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-ditertiary butylphenyl) benzotriazole, 2- (2-Hydroxy-3,5-ditertiary butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3-third butyl-5-methylphenyl) -5-chlorobenzotriazole, 2-( 2-Hydroxy-3-tertiary butyl-5-carbooctoxyethylphenyl) benzotriazole, 2- (2-hydroxy-5-third octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-diku) Examples thereof include 2-hydroxyphenylbenzotriazole compounds such as milphenyl) benzotriazole and 2,2'-methylenebis (4-thioctyl-6-benzotriazolylphenol).

The content of the ultraviolet absorber in the polyolefin sheet is, for example, 0.05 parts by mass or more, may be 0.1 parts by mass or more, or 0.4 parts by mass or more with respect to 100 parts by mass of the polyolefin resin. There may be. If the content of the UV absorber is too low, the weather resistance of the polyolefin sheet may not be improved. On the other hand, the content of the ultraviolet absorber in the polyolefin sheet is, for example, 5.0 parts by mass or less, may be 3.0 parts by mass or less, or 1.0 part by mass with respect to 100 parts by mass of the polyolefin resin. It may be as follows. If the content of the UV absorber is too high, it may lead to poor appearance due to bleed-out and, depending on the type of UV absorber, poor appearance due to coloring.

(C) Heavy Metal Inactivating Agent The polyolefin sheet may contain a heavy metal inactivating agent. When the polyolefin sheet comes into contact with, for example, an iron pipe, the polyolefin resin may be decomposed due to the influence of heavy metal elements (for example, Fe element) contained in the iron pipe. Specifically, heavy metal elements form oxides, and the catalytic action of the oxides may decompose the polyolefin resin. Examples of heavy metal elements 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 an oxalic acid derivative, a salicylic acid derivative, a hydrazide derivative and the like. , CDA-6 (all manufactured by Adeka Corporation), Cel-180, Inganox MD 1024 (all manufactured by BASF Corporation) and the like can be exemplified. In addition, Japanese Patent Publication No. 37-14484, Japanese Patent Publication No. 39-9072, Japanese Patent Publication No. 39-12454, Japanese Patent Publication No. 39-19541, Japanese Patent Publication No. 40-12293, Japanese Patent Publication No. 40-18852, Tokusho 42-4356, Tokusho 42-4596, Tokusho 42-13247, Tokusho 43-6538, Tokusho 43-18606, Tokusho 47-27624, Tokukousho 48-36837, Japanese Patent Publication No. 49-15466, Japanese Patent Publication No. 52-22834, Japanese Patent Publication No. 54-43537, Japanese Patent Publication No. 54-90143, US Pat. No. 3,357,944, US Pat. No. 3,376,907. It may be exemplified in the specification, the French Patent No. 148105, the French Patent No. 1495830, and the like.

The content of the heavy metal deactivating agent in the polyolefin sheet is, for example, 0.05 parts by mass or more, may be 0.1 parts by mass or more, or 0.4 parts by mass or more with respect to 100 parts by mass of the polyolefin resin. May be. If the content of the heavy metal deactivating agent is too low, copper damage may not be sufficiently suppressed. On the other hand, the content of the heavy metal deactivating agent in the polyolefin sheet is, for example, 5.0 parts by mass or less, may be 3.0 parts by mass or less, or 1.0 part by mass with respect to 100 parts by mass of the polyolefin resin. It may be less than or equal to a part . If the content of the heavy metal deactivating agent is too high, it may lead to poor appearance due to poor dispersion.

(D) Other Additives The polyolefin sheet contains an appropriate amount of known additives such as other lubricants, heat stabilizers, pigments, modifiers, flame retardants, antistatic agents, reinforcing agents, and fungicides. May be good.

(5) Method for producing a polyolefin sheet The method for producing a polyolefin sheet is not particularly limited as long as it is a method for obtaining a target polyolefin sheet, and for example, a polyolefin resin, a light stabilizer, and an inorganic filler may be used. Examples thereof include a manufacturing method including a step of producing a resin composition containing the resin composition and a step of forming the resin composition into a sheet (filming) to prepare a polyolefin sheet.

The method for producing the resin composition is not particularly limited, but a method for producing a resin composition by melt-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, an extruder and the like. The heating temperature for melt-kneading is, for example, 150 ° C. or higher and 200 ° C. or lower.

Examples of the method for forming the resin composition into a sheet include known molding methods such as extrusion stretching processing, calendar processing, and extrusion molding. For example, in the case of producing a sheet (porous polyolefin sheet) in which the polyolefin sheet has voids inside, a biaxial stretching / stretching process that combines longitudinal stretching and transverse stretching is preferable in the extrusion stretching process. On the other hand, for example, when the polyolefin sheet is a sheet having voids inside (porous polyolefin sheet), especially when the thickness of the polyolefin sheet is thin, calendar processing suitable for producing a sheet having a uniform thickness is possible. preferable. Calendering is suitable because of the structure of the molding machine, it is easy to handle the size and type of resin, and it is easy to handle small lots. Further, for example, when a resin composition having a high content of an inorganic filler is used, it is preferable to mold it by calendar processing. When a large amount of inorganic filler is contained, for example, when molded by extrusion molding, the surface of the obtained sheet becomes rough and the sheet is easily torn, but molding by calendar processing does not cause such inconvenience and the surface is smooth. Sheets can be manufactured. Further, the superiority of the calendar processing when the resin composition having a high content of the inorganic filler is used is particularly remarkable when the thickness of the polyolefin sheet is as thin as, for example, about 30 μm or more and 70 μm or less.

2. 2. Reinforcing Sheet The reinforcing sheet in the present disclosure is a member arranged on one surface of the polyolefin sheet. The reinforcing sheet is a sheet that reinforces the polyolefin sheet. The agricultural sheet may have another layer between the polyolefin sheet and the reinforcing sheet, or may be in contact with each other without the other layer.

The reinforcing sheet in the present disclosure may be any member as long as it can impart a predetermined strength to prevent the agricultural sheet from tearing, and examples thereof include non-woven fabrics and woven fabrics.

Among the thermoplastic resins, the material of the nonwoven fabric or the woven fabric is preferably a polyolefin resin, an ester resin or an amide resin. Examples of the non-woven fabric include fiber orthogonal non-woven fabric, long-fiber non-woven fabric, short-fiber non-woven fabric, wet non-woven fabric, dry non-woven fabric, air-laid non-woven fabric, card-type non-woven fabric, parallel non-woven fabric, cloth-type non-woven fabric, random non-woven fabric, spunbond non-woven fabric, and melt blown non-woven fabric. , Flash-spun non-woven fabric, chemical bond non-woven fabric, water flow entanglement non-woven fabric, needle punch non-woven fabric, stitch bond non-woven fabric, thermal bond non-woven fabric, burst fiber non-woven fabric, tow open fiber non-woven fabric, split fiber non-woven fabric, composite non-woven fabric, laminated non-woven fabric, coated non-woven fabric, laminated non-woven fabric, etc. Can be mentioned.

The fiber orthogonal nonwoven fabric is a nonwoven fabric in which two or more stretched films are laminated so that the stretching directions are orthogonal to each other, and examples thereof include Warif (registered trademark) manufactured by JX ANCI Co., Ltd. The basis weight of the fiber orthogonal nonwoven fabric is preferably 5 g / m ² or more and 100 g / m ² or less, and 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, it is possible to obtain a reinforcing sheet having sufficient strength. Further, the fiber diameter of the long fiber nonwoven fabric is preferably, for example, 3 μm or more and 20 μm or less. On the other hand, the fiber diameter of the staple fiber nonwoven fabric is preferably less than, for example, 3 μm.

On the other hand, as another example of the reinforcing sheet, as a cloth-type nonwoven fabric, for example, the polyolefin mesh cloth disclosed in Japanese Patent Application Laid-Open No. 2007-259734 can be mentioned. Polyolefin mesh cloth is preferably made of polyethylene in consideration of adhesiveness in extrusion molding. Since the content of the polyolefin mesh cloth can be the same as that described in the above publication, the description here is omitted. The thickness of the cloth-type nonwoven fabric is preferably 30 μm or more and 100 μm or less, and more preferably 50 μm or more and 80 μm or less.

The reinforcing sheet preferably contains a resin. The resin may be a thermoplastic resin or a thermosetting resin, but the former is preferable. In particular, the resin used for the reinforcing sheet is preferably a polyolefin resin. That is, in the present disclosure, the reinforcing sheet is preferably a fiber orthogonal nonwoven fabric containing a polyolefin-based resin. This is because the reinforcing sheet contains a polyolefin resin, which is excellent in heat resistance, water resistance, chemical resistance, and cost. Specific examples of the polyolefin-based resin include polyethylene-based resin and polypropylene-based resin, and among them, polyethylene-based resin is preferable.

Examples of the polyethylene-based resin include high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ultra-low-density polyethylene (VLDPE), and the like. 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 the high-density polyethylene is excellent in weather resistance and tensile strength, and the sheet containing the high-density polyethylene has no slack even in a long roll and is less likely to cause an appearance defect due to whitening during bending. In particular, when the resin component of the reinforcing sheet is only polyethylene-based resin, it is preferable to use at least one of high-density polyethylene and linear low-density polyethylene.

Further, the polyethylene resin has a melt flow rate (temperature 230 ° C., load 2.16 kg) measured in accordance with JIS K 7210 of 0.1 g / 10 minutes or more and 4.0 g / 10 minutes or less. It is more preferably 0.4 g / 10 minutes or more and 2.0 g / 10 minutes or less.

Further, as the thermoplastic resin, an acrylic resin, a styrene resin, a vinyl fluoride resin, an amide resin, an ester resin and the like can be used. Examples of the acrylic resin include polymethyl acrylate, polymethyl methacrylate, and ethylene-ethyl acrylate copolymer. Examples of the styrene resin include a butadiene-styrene copolymer, an acrylonitrile-styrene copolymer, polystyrene, a styrene-butadiene-styrene copolymer, a styrene-isoprene-styrene copolymer, a styrene-acrylic acid copolymer and the like. Can be mentioned. Examples of the vinyl fluoride resin include vinyl chloride resin, polyvinyl fluoride, polyvinylidene fluoride and the like. 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 polyplybutylene terephthalate. Further, as the thermoplastic resin, polycarbonate, polyphenylene oxide, polyacetal, polyphenylene sulfide, silicone resin, thermoplastic urethane resin, polyether ether ketone, polyetherimide, thermoplastic elastomer and the like may be used.

The thermoplastic resin contained in the reinforcing sheet and the thermoplastic resin contained in the above-mentioned polyolefin sheet may be the same or different.

The thickness of the reinforcing sheet is not particularly limited, but is preferably, for example, 5 μm or more and 150 μm or less, and preferably 50 μm or more and 100 μm or less.

The reinforcing sheet in the present disclosure may have a single-layer structure or a multi-layer structure. As an agricultural sheet having a single-layer structure reinforcing sheet, for example, as shown in FIG. 2A, an agricultural sheet 10 having a polyolefin sheet 1, an adhesive layer 3, and a single-layer structure reinforcing sheet 2 in this order. Can be mentioned.

On the other hand, as an agricultural sheet having a multi-layered reinforcing sheet, for example, as shown in FIG. 2B, agriculture having a polyolefin sheet 1, an adhesive layer 3, and a multi-layered reinforcing sheet 2 in this order. Sheet 10 is mentioned. The reinforcing sheet 2 having a multi-layer structure has a first reinforcing sheet 2a, an adhesive layer 4 for reinforcing sheets, and a second reinforcing sheet 2b in this order. Although not shown, the plurality of reinforcing sheets may be in contact with each other (for example, fused) without interposing the adhesive layer. Further, the type of the adhesive layer for the reinforcing sheet is not particularly limited, and may be the same as the content described in the section "3. Adhesive layer" described later.

The thickness of the reinforcing sheet is not particularly limited, but is preferably, for example, 10 μm or more and 200 μm or less, and preferably 20 μm or more and 180 μm or less. When the reinforcing sheet has a multi-layer structure, it is preferable that the thickness of each layer constituting the reinforcing sheet is within the above-mentioned range. Further, the agricultural sheet may have a reinforcing sheet on the outermost surface or may have a reinforcing sheet inside.

3. 3. Adhesive layer In the agricultural sheet, the polyolefin sheet and the reinforcing sheet may be laminated through the adhesive layer, or may be directly laminated without the adhesive layer. The adhesive layer is composed of an adhesive or an extruded coating. The adhesive layer is not particularly limited, but is preferably an extruded coating.

For extruded coatings, resins that can be melted by heat and fused to each other can be used. Specifically, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear (linear) low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionoma-resin, ethylene-acrylic acid co-weight. Combined, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyolefin such as polyethylene or polypropylene Acid-modified polyolefin resin modified with unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, polyvinyl acetate resin, poly (meth) acrylic resin , Polyvinyl chloride resin, and other resins can be used.

These may be used alone or in combination of two or more. Among these, polyethylene-based resins are suitable, low-density polyethylene, linear low-density polyethylene are preferable, and low-density polyethylene is more preferable. Low-density polyethylene has excellent processability, excellent adhesion to polyethylene non-woven fabric, and is 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, and is 0. It is more preferably .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 extrusion coating.

Further, in order to strengthen the adhesion of the polyolefin sheet, an anchor coating agent may be coated on the polyolefin sheet to provide an anchor coating agent layer. Examples of the anchor coating agent forming the anchor coating agent layer include an organic titanium-based anchor coating agent such as alkyl titanate, an isocyanate-based anchor coating agent, a polyethyleneimine-based anchor coating agent, a polybutadiene-based anchor coating agent, and the like. .. In the present disclosure, similarly to the above, the anchor coating agent is coated with, for example, roll coating, gravure coating, knife coating, dip coating, spray coating, or other coating method, and the solvent, diluent, etc. are dried. , Anchor coating agent layer can be formed. In the above, the coating 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, examples of the laminating adhesive forming the anchor coating agent include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and polymethylenepolyphenylene polyisocyanate, or hexamethylene diisocyanate. , Polyether polyurethane resin, polyester obtained by reaction of polyfunctional isocyanate such as aliphatic polyisocyanate such as xylylene diisocyanate with hydroxyl group-containing compound such as polyether polyol, polyester polyol, polyacrylate polyol, etc. It is preferable to use a polyurethane-based resin or a laminating adhesive containing a polyacrylate polyurethane-based resin as a main component.

The anchor coating agent layer can form a thin film that is soft, highly flexible, and highly flexible, and can improve the degree of tensile elongation thereof. Further, it acts as a film having flexibility, flexibility and the like on the polyolefin sheet, can improve the aptitude for processing the polyolefin sheet at the time of laminating processing, and can prevent peeling failure at the time of use.

The anchor coating agent layer in the present disclosure preferably has a tensile elongation of 100% or more and 300% or less based on JIS standard K7113. The tensile elongation of the anchor coating agent layer can improve the tight adhesion between the polyolefin sheet and the reinforcing sheet. Therefore, the laminating strength between the polyolefin sheet and the reinforcing sheet can be increased.

The thickness of the adhesive layer formed by the extruded coating is not particularly limited, but is preferably thinner from the viewpoint of handleability of the agricultural sheet. The thickness of the adhesive layer is preferably 10 μm or more and 20 μm or less.

4. Agricultural sheet The agricultural sheet has the above-mentioned polyolefin sheet and reinforcing sheet. The agricultural sheet preferably has a polyolefin sheet on the outermost surface. The agricultural sheet preferably has a tear strength of 1.4 N or more by the Elmendorf tear method. The tear strength of the agricultural sheet by the Elmendorf tearing method is, for example, 1.4 N or more, preferably 2.5 N or more. On the other hand, the tear strength of the agricultural sheet is, for example, 25 N or less, and may be 20 N or less.

In addition, agricultural sheets have a high visible light reflectance. The average reflectance of visible light (wavelength 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 measurement conditions for the average reflectance of visible light will be described in detail in Examples.

The agricultural sheet may or may not have a light reflecting layer. When the light reflection layer is provided, the visible light reflectance can be made higher, the coloring of fruits can be promoted, and the rise in soil 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 or Si, calcium carbonate, barium sulfate and the like. Examples of the resin component include polyurethane-based resin and polyester-based resin. Examples of the polyurethane-based resin include polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, and polycaprolactum polyurethane. The location of the light reflecting layer is not particularly limited, and may be the outermost surface of the agricultural sheet or the inside. Further, it is preferable that the light reflecting layer is provided on the side opposite to the reinforcing sheet with the porous substrate sheet as a reference. The thickness of the light reflecting layer is, for example, 0.5 μm or more and 4 μm or less.

Agricultural sheets preferably have high UV reflectance. This is because it can exert a pest repellent effect. The average reflectance of ultraviolet rays (wavelength 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, preferably 60% or more, and preferably 80% or more. More preferred. The “surface on the reinforcing sheet side of the agricultural sheet” refers to the surface on the side opposite to the polyolefin sheet side with respect to the reinforcing sheet.

The thickness of the agricultural sheet is not particularly limited, but is preferably, for example, 50 μm or more and 200 μm or less, and preferably 80 μm or more and 150 μm or less. The agricultural sheet may have a plurality of through holes penetrating from one side to the other. The ratio of through holes is, for example, 10,000 pieces / m ² or more and 1 million pieces / m ² or less, and preferably 100,000 pieces / m ² or more and 700,000 pieces / m ² or less.

5. Method for Manufacturing Agricultural Sheet The method for manufacturing an agricultural sheet is not particularly limited as long as the target agricultural sheet can be obtained, and for example, a method for heat-sealing a polyolefin sheet and a reinforcing sheet, a polyolefin sheet and a reinforcing sheet, etc. Examples thereof include a method of laminating through an adhesive layer and a method of laminating a polyolefin sheet and a reinforcing sheet via an adhesive layer composed of an extruded coating. In the agricultural sheet of the present disclosure, a non-woven fabric is suitable as the reinforcing sheet, and therefore, as a method for producing the agricultural sheet, a method of laminating via an adhesive layer composed of an extruded coating is preferable.

FIG. 3 is a schematic cross-sectional view showing an example of a method for manufacturing an agricultural sheet, and specifically shows a method for manufacturing an agricultural sheet by extrusion coating. In FIG. 3, an anchor coating agent is applied to the surface of the polyolefin sheet 1 to form an anchor coating agent layer 5 (FIG. 3A). Next, the adhesive composition 3x is applied to the surface of the anchor coating agent layer 5 (FIG. 3 (b)). Next, the adhesive layer 3 is formed by drying the adhesive composition 3x (FIG. 3 (c)). Next, the polyolefin sheet 1 and the reinforcing sheet 2 are laminated via the adhesive layer 3 (FIG. 3 (d)). As a result, an agricultural sheet 10 having a polyolefin sheet 1, an anchor coating agent layer 5, an adhesive layer 3 and a reinforcing sheet 2 in this order can be obtained (FIG. 3 (e)).

The adhesive composition may further contain a solvent in addition to the adhesive. The adhesive is as described above. On the other hand, as the solvent, for example, 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, and ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. , Diethylene glycol methyl ethers, ethers such as tetrahydrofuran and dioxane, aromatics such as toluene and xylene, halogenated hydrocarbons and the like.

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 at which the adhesive composition is dried varies depending on the type of the polyolefin sheet and the solvent, but is, for example, 90 ° C. or lower, preferably 70 ° C. or lower. Further, vacuum drying or other vacuum drying may be performed. Further, the drying time is appropriately selected according to the type of the adhesive.

When the polyolefin sheet 1 and the reinforcing sheet 2 are bonded by extrusion coating, it is preferable to control the pressure by tension. In this case, it is preferable to control the polyolefin sheet of the first paper feed at, for example, 100 N or more and 300 N or less, and more preferably 150 N or more and 250 N or less. The reinforcing sheet for the second paper feed is preferably controlled at, for example, 100 N or more and 180 N or less, and more preferably 120 N or more and 150 N or less in order to prevent curling of the entire sheet.

Further, the agricultural sheet may be manufactured by using the dry laminating method. For example, in the dry laminating method, it is preferable to perform laminating in a temperature environment in which the polyolefin sheet is not thermally deformed. For example, in the dry laminating method, it is not necessary to heat the polyolefin sheet at the time of laminating, but heating may be performed as long as the temperature does not cause thermal deformation of the polyolefin sheet.

The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. It is included in the technical scope of the invention.

[Example 1]
(Preparation of polyolefin sheet)
HDPE film (high density polyethylene (HDPE, melting point 130 ° C, MFR (190 ° C, 2160 g): 0.5 g / 10 min) 100 parts by mass as a polyolefin resin, 2 (2'-hydroxy-5'-tert) as an ultraviolet absorber -Octylphenyl) benzotriazole 0.1 part by mass, NOR type hindered amine light stabilizer (Adecastab LA-81) (bis (1-undecaneoxy-2,2,6,6-tetramethylpiperidine-4) -Il) carbonate) 0.4 parts by mass, as a phenolic antioxidant, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propinate] 0.1 parts by mass, inorganic filling 20 parts by mass of calcium carbonate as agent 1 (heavy calcium carbonate (PE master batch with 60% filling rate): 8 parts by mass of PE content), 40 parts by mass of titanium pigment as inorganic filler 2 (PE with 80% filling rate) Master batch: PE content (8 parts by mass) was mixed and melt-kneaded at 180 ° C. using a Banbury mixer.

The total amount of the polyolefin-based resin contained in the obtained kneaded product is 116 parts by mass, and the content of the NOR-type hindered amine-based light stabilizer is 0.34 parts by mass with respect to 100 parts by mass of the polyolefin-based resin. .. The content of the inorganic fillers 1 and 2 with respect to 100 parts by mass of the polyolefin resin is 37.9 parts by mass .

Next, the obtained kneaded product was supplied to a 12-inch diameter x 30 L common head type mixing roll (rotation speed: 18 rpm) and rolled at a roll temperature of 165 ° C. or higher and 190 ° C. or lower to obtain a polyolefin sheet having a thickness of 30 μm. Manufactured.

(Preparation of agricultural sheet)
Polyolefin sheets and reinforcing sheets were prepared. As a reinforcing sheet, a polyethylene cloth (thickness 65 μm) made of polyethylene resin is prepared, a urethane-based anchor coating agent is coated on the polyolefin sheet, and an anchor coating agent layer having a thickness of 0.5 g / m ² (dry state) is applied. Formed. Further, low density polyethylene (LDPE, MI = 8.0, density = 0.92) is extruded and coated on the above anchor coating agent layer to a thickness of 15 μm while being subjected to ozone treatment, and attached to a reinforcing sheet. Together, an agricultural sheet was made. The molten resin temperature of LDPE was 320 ° C.

[Example 2]
Agricultural sheets were produced in the same manner as in Example 1 except that linear low density polyethylene (L-LDPE, melting point 125 ° C., MFR (190 ° C., 2160 g): 2.0 g / 10 min) was used as the polyolefin resin. did.

[Example 3]
(Preparation of porous polypropylene sheet)
As the resin composition constituting the inner layer of the sheet, 65.5% by mass of propylene homopolymer (manufactured by Japan Polychem Corporation, trade name "Novatec PP: MA-8", melting point 164 ° C.), high-density polyethylene (Japan). Made by Polychem Corporation, trade name "Novatec HD: HJ580", melting point 134 ° C, density 0.960 g / cm ³ ) is 6.5% by mass, and calcium carbonate powder with an average particle size of 1.5 μm is 28% by mass. A non-stretched sheet was obtained from a resin composition consisting of% by using an extruder. Next, this unstretched sheet was stretched four times in the vertical direction to obtain a uniaxially stretched sheet.

On the other hand, as the resin composition constituting the outer layer of the sheet, the same material as above has 51.5% by mass of the propylene homopolymer, 3.5% by mass of the high-density polyethylene, and an average particle size of 1.5 μm. 42% by mass of calcium carbonate powder, 3% by mass of titanium oxide powder having an average particle diameter of 0.8 μm, and 0.1 part by mass of 2 (2'-hydroxy-5'-tert-octylphenyl) benzotriazole as an ultraviolet absorber. , NOR type hindered amine-based photostabilizer (Adeca, Adecastab LA-81) (bis (1-undecaneoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate) 0.3 parts by mass, As a phenolic antioxidant, a resin composition consisting of 0.1 parts by mass of pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propinate] was prepared using another extruder. It was melt-kneaded and extruded from dies on both sides of the surface of the uniaxially stretched sheet to obtain a laminated sheet having a layer structure of an outer layer, an inner layer, and an outer layer.

Next, by stretching this laminated sheet 7 times in the lateral direction and slitting the selvage portion, the thickness is 70 μm, and the layer structure of the outer layer (15 μm), the inner layer (40 μm), and the outer layer (15 μm) is fine. A porous polypropylene sheet containing voids was obtained.

(Preparation of agricultural sheet)
An agricultural sheet was produced in the same manner as in Example 1 except that the obtained porous polypropylene sheet was used as the polyolefin sheet.

[Comparative Example 1]
(Preparation of porous polypropylene sheet)
A porous polypropylene sheet was obtained in the same manner as in Example 3.

(Preparation of agricultural sheet)
As a reinforcing sheet, an L-LDPE film (linear low density polyethylene film, thickness 30 μm, TUX TC-S, manufactured by Mitsui Chemicals Tohcello Co., Ltd.) was prepared, and the obtained porous polypropylene sheet and the above reinforcing sheet were used in Example 1. Agricultural sheets were manufactured by laminating them in the same manner as above.

[Comparative Example 2]
The porous polypropylene sheet alone obtained in the same manner as in Example 3 was used as an agricultural sheet.

[evaluation]
(Spelling needle holding strength (N))
The strength (spelling needle holding strength) in JIS A6930 was measured for the agricultural sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 1.

(Visible light reflectance measurement)
Visible light reflectance was measured on the agricultural sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2. In the visible light reflectance measurement, using an ultraviolet / visible / near-infrared spectrophotometer (Shimadzu UV-3600) and an integrating sphere accessory (ISR-3100), the visible region is 380 nm or more and 780 nm or less at an incident angle of 8 °. The reflectance (total reflectance) of the above was measured, and the average reflectance was obtained. As the standard plate, Spectralon (manufactured by Teflon (registered trademark)) manufactured by Lovesphere Inc. of the United States was used. The measurement surface was the surface on the polyethylene sheet side of the agricultural sheet. The results are shown in Table 1.

(Agricultural sheet damaged 6 months after laying)
With respect to the agricultural sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2, it was confirmed whether or not the agricultural sheets were damaged 6 months after the laying. When the agricultural sheet was not damaged, it was evaluated as ○, and when it was damaged, it was evaluated as ×.

1 ... Polyolefin sheet 2 ... Reinforcing sheet 3, 4 ... Adhesive layer 5 ... Anchor coating agent layer 10 ... Agricultural sheet 20 ... Pin

Claims (3)

It has a polyolefin sheet containing a polyolefin resin and an inorganic filler, and a reinforcing sheet.
The thickness of the polyolefin sheet is 150 μm or less, and the thickness is 150 μm or less.
The strength (spelling needle holding strength) in JIS A6930 is 35N or more.
The inorganic filler contains at least one of calcium carbonate and titanium oxide.
The content of the inorganic filler in the polyolefin sheet is 30 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the polyolefin-based resin.
The polyolefin sheet is an agricultural sheet containing a NOR-type hindered amine-based light stabilizer.
The polyolefin sheet is an agricultural sheet which is a sheet having no voids . The agricultural sheet according to claim 1, wherein the polyolefin-based resin is high-density polyethylene or linear low-density polyethylene. The agricultural sheet according to claim 1 or 2, wherein the reinforcing sheet contains a polyethylene-based resin.

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