JP2015167537A - Agricultural film and agricultural covering material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agricultural film and an agricultural covering material being excellent in the affinity to an antifogging agent, transparency, ultraviolet ray permeability, and weather resistance.SOLUTION: An agricultural film comprises a fluorine-containing copolymer having a fluorine-containing olefin unit and a vinyl alcohol unit.

Description

The present invention relates to an agricultural film and an agricultural covering material.

Conventionally, films such as polyethylene, ethylene-vinyl acetate copolymer, polyester resin, and soft vinyl chloride resin have been used as agricultural covering materials for tunnel houses and pipe houses, among which workability, price, heat retention, etc. In view of the advantages, soft vinyl chloride resin films are frequently used.

In addition, for the purpose of improving weather resistance and the like, use of a film of a tetrafluoroethylene-ethylene copolymer (hereinafter also referred to as ETFE) has been studied (for example, see Patent Documents 1 and 2).

By the way, the resin film used for the agricultural covering material alone does not have high surface hydrophilicity, so it is likely to cause dew condensation and cloudiness, which reduces the transmittance of sunlight and adversely affects the growth of crops. Sometimes. For this reason, as a covering material for agriculture, in order to prevent dew condensation or fogging, a material in which a hydrophilic coating film is formed by applying an antifogging agent to the surface of a resin film is usually used. For example, Patent Documents 3 to 6 describe that the surface of an ETFE film is subjected to a surface treatment such as corona treatment and an antifogging agent is applied on the surface.

JP 2001-206913 A JP 11-343315 A JP 2007-063477 A JP 2009-234048 A Japanese Patent No. 2535185 Japanese Patent No. 4294152

Since non-fluorinated resin films such as soft vinyl chloride resin films are easily deteriorated by ultraviolet rays, ultraviolet absorbers are generally blended when used for agricultural coating materials. However, since films containing UV absorbers block UV rays, cultivation of crops that require UV rays (eg, eggplants, certain flowers) and bees and mahana abs that require UV rays to operate There is a problem that it is not suitable for cultivation of crops (eg, strawberries, melons, watermelons, peppers, etc.) pollinated by other insects.

In addition, if an ETFE film is used, deterioration due to ultraviolet rays is suppressed as compared with a soft vinyl chloride resin film or the like. However, as described in Patent Documents 3 to 6, surface treatment is performed to apply an antifogging agent. Therefore, there is a problem that the manufacturing process is complicated and the manufacturing cost increases.

This invention is made | formed in view of the said present condition, and provides the agricultural film excellent in affinity with an antifogging agent, transparency, ultraviolet-ray permeability, and a weather resistance, and an agricultural covering material. Objective.

That is, the present invention is an agricultural film comprising a fluorine-containing copolymer having a fluorine-containing olefin unit and a vinyl alcohol unit.

This invention is also an agricultural covering material which has the said film and the anti-fogging agent layer which consists of an anti-fogging agent provided on the at least one surface of this film.

ADVANTAGE OF THE INVENTION According to this invention, the agricultural film excellent in affinity with an antifogging agent, transparency, ultraviolet-ray permeability, and a weather resistance, and an agricultural covering material can be provided.

Hereinafter, the present invention will be specifically described.

The agricultural film of the present invention (hereinafter also referred to as the film of the present invention) comprises a fluorine-containing copolymer having a fluorine-containing olefin unit and a vinyl alcohol unit.

The agricultural film of this invention is excellent in affinity with the antifogging agent mentioned later. For this reason, it is possible to directly apply the antifogging agent without applying surface treatment or providing an adhesive layer on the surface of the film of the present invention, which can simplify the manufacturing process and reduce the manufacturing cost. It is.

Since the agricultural film of the present invention is not easily deteriorated by ultraviolet rays, sufficient weather resistance can be exhibited even without containing an ultraviolet absorber. For this reason, ultraviolet rays are not shielded more than necessary, and the growth of crops that require ultraviolet rays and the flying properties of insects that contribute to pollination are improved.

Since the agricultural film of the present invention is also excellent in transparency, it sufficiently transmits sunlight. Therefore, the growth of the crop is improved.

The fluorine-containing copolymer constituting the agricultural film of the present invention has a fluorine-containing olefin unit and a vinyl alcohol unit (—CH ₂ —CH (OH) —).

The said fluorine-containing olefin unit represents the polymerization unit based on a fluorine-containing olefin. The fluorine-containing olefin is a monomer having a fluorine atom.

Examples of the fluorine-containing olefin include tetrafluoroethylene [TFE], vinylidene fluoride [VdF], chlorotrifluoroethylene [CTFE], vinyl fluoride, hexafluoropropylene [HFP], hexafluoroisobutene, CH ₂ = CZ. ¹ (CF ₂ ) _n1 Z ² (wherein Z ¹ is H, F or Cl, Z ² is H, F or Cl, and n1 is an integer of 1 to 10), CF ₂ = CF-ORf ¹ (wherein Rf ¹ represents a perfluoroalkyl group having 1 to 8 carbon atoms) and CF ₂ = CF-OCH ₂ -rf ² (wherein, Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms) selected from the group consisting of alkyl perfluorovinyl ether derivative represented by the It is preferably be at least one kind of fluorine-containing olefin.

Examples of the monomer represented by CH ₂ = CZ ¹ (CF ₂ ) _n1 Z ² include CH ₂ = CFCF ₃ , CH ₂ = CHCF ₃ , CH ₂ = CFCHF ₂ and CH ₂ = CClCF ₃ .

Examples of the PAVE include perfluoro (methyl vinyl ether) [PMVE], perfluoro (ethyl vinyl ether) [PEVE], perfluoro (propyl vinyl ether) [PPVE], perfluoro (butyl vinyl ether), etc. Among them, PMVE PEVE or PPVE is more preferable.

As the alkyl perfluorovinyl ether derivative, those in which Rf ² is a perfluoroalkyl group having 1 to 3 carbon atoms are preferable, and CF ₂ = CF—OCH ₂ —CF ₂ CF ₃ is more preferable.

As said fluorine-containing olefin, at least 1 sort (s) selected from the group which consists of TFE, CTFE, and HFP is more preferable, and TFE is still more preferable.

The fluorine-containing copolymer preferably has a fluorine-containing olefin unit content of 40 mol% or more in the fluorine-containing copolymer, the fluorine-containing olefin unit is from 40 mol% to 80 mol%, and vinyl alcohol. More preferably, the unit is 20 mol% or more and 60 mol% or less. When the content of each monomer unit of the fluorine-containing copolymer in the present invention is within such a range, the obtained film has excellent mechanical properties, durability, and weather resistance. As the content of each monomer unit, the fluorine-containing olefin unit is 45 mol% or more and 75 mol% or less, the vinyl alcohol unit is more preferably 25 mol% or more and 55 mol% or less, and the fluorine-containing olefin unit is 50 mol% or less. It is particularly preferred that the content is from mol% to 70 mol%, and the vinyl alcohol unit is from 30 mol% to 50 mol%.

The fluorine-containing copolymer preferably has an alternating ratio of fluorine-containing olefin units and vinyl alcohol units of 94% or less. When the alternating rate is in such a range, an effect that the obtained film is excellent in flexibility can be obtained. More preferably, it is 90% or less, and particularly preferably 80% or less. Further, it is preferably 30% or more, more preferably 35% or more, and further preferably 40% or more. If the alternating rate is too low, the heat resistance may decrease, which is not preferable.

The alternating rate of the fluorinated olefin unit and the vinyl alcohol unit was determined by performing ¹ H-NMR measurement of the fluorinated copolymer using a solvent in which the fluorinated copolymer such as heavy acetone is dissolved, and calculating from the following formula: It can be calculated as the alternating rate of chaining.
Alternating rate (%) = C / (A + B + C) × 100
A: The number of V combined with two Vs such as -VVVV- B: The number of V combined with V and T as -VVT- C: -TV- Number of V bonded to two T like T- (T: fluorine-containing olefin unit, V: vinyl alcohol unit)
The number of V units of A, B, and C is calculated from the intensity ratio of H of the main chain bonded to the tertiary carbon of the vinyl alcohol unit (—CH ₂ —CH (OH) —) of ¹ H-NMR measurement. The estimation of the strength ratio of H in the main chain by ¹ H-NMR measurement is carried out with the fluorine-containing copolymer before hydroxylation.

The fluorine-containing copolymer is further represented by —CH ₂ —CH (O (C═O) R) — (wherein R represents a hydrogen atom or a hydrocarbon group having 1 to 17 carbon atoms). It may have a vinyl ester monomer unit. Thus, it is also one of the preferred embodiments of the present invention that the fluorinated copolymer in the present invention has a fluorinated olefin unit, a vinyl alcohol unit, and a vinyl ester monomer unit. Furthermore, it is a fluorine-containing olefin / vinyl alcohol / vinyl ester monomer copolymer consisting essentially of a fluorine-containing olefin unit, a vinyl alcohol unit and a vinyl ester monomer unit. One.

The vinyl ester monomer unit is a monomer represented by —CH ₂ —CH (O (C═O) R) — (wherein R represents a hydrogen atom or a hydrocarbon group having 1 to 17 carbon atoms). Although it is a unit, as R in the said formula, a C1-C11 alkyl group is preferable and a C1-C5 alkyl group is more preferable. Particularly preferred is an alkyl group having 1 to 3 carbon atoms.

Examples of the vinyl ester monomer unit include monomer units derived from the following vinyl esters.
Vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valelate, vinyl isovalerate, vinyl caproate, vinyl heptylate, vinyl caprylate, vinyl pivalate, vinyl pelargonate, vinyl caprate, Vinyl laurate, vinyl myristate, vinyl pentadecylate, vinyl palmitate, vinyl margarate, vinyl stearate, vinyl octylate, Veova-9 (manufactured by Showa Shell Sekiyu KK), Veova-10 (Showa Shell Sekiyu KK) )), Vinyl benzoate, vinyl versatate.
Among these, monomer units derived from vinyl acetate, vinyl propionate, and vinyl versatate are preferable. More preferred are vinyl acetate monomer units and vinyl propionate monomer units, and even more preferred are vinyl acetate monomer units.

When the fluorine-containing copolymer has a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ester monomer unit, the content of each monomer unit is 40 mol% or more and 80 mol% or less of the fluorine-containing olefin unit. The vinyl alcohol unit is preferably more than 0 mol% and less than 60 mol%, and the vinyl ester monomer unit is preferably more than 0 mol% and less than 60 mol%. When the content of each monomer unit is within such a range, the obtained film has excellent mechanical properties, durability, and weather resistance. As the content of each monomer unit, the fluorine-containing olefin unit is from 45 mol% to 75 mol%, the vinyl alcohol unit is from 5 mol% to 50 mol%, and the vinyl ester monomer unit is from 5 mol% to 50 mol%. More preferably, the fluorine-containing olefin unit is 50 mol% or more and 70 mol% or less, the vinyl alcohol unit is 10 mol% or more and 40 mol% or less, and the vinyl ester monomer unit is 10 mol% or more. More preferably, it is 40 mol% or less.

When the fluorine-containing copolymer has a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ester monomer unit, the alternating rate of the fluorine-containing olefin unit, the vinyl alcohol unit, and the vinyl ester monomer unit is 94% or less. Is preferred. When the alternating rate is in such a range, an effect that the obtained film is excellent in flexibility can be obtained. More preferably, it is 90% or less, and particularly preferably 80% or less. Further, it is preferably 30% or more, more preferably 35% or more, and further preferably 40%. If the alternating rate is too low, the heat resistance may decrease, which is not preferable.

The alternating rate of the fluorinated olefin unit, the vinyl alcohol unit, and the vinyl ester monomer unit is determined by performing ¹ H-NMR measurement of the fluorinated copolymer using a solvent in which the fluorinated copolymer such as heavy acetone is dissolved, It can be calculated as an alternating rate of three chains from the following formula.
Alternating rate (%) = C / (A + B + C) × 100
A: The number of V combined with two Vs such as -VVVV- B: The number of V combined with V and T as -VVT- C: -TV- Number of Vs bonded to two Ts such as T- (T: fluorinated olefin unit, V: vinyl alcohol unit or vinyl ester monomer unit)
The number of V units of A, B, and C is the vinyl alcohol unit (—CH ₂ —CH (OH) —) and vinyl ester monomer unit (—CH ₂ —CH (O (C═O)) of ¹ H-NMR measurement. Calculated from the intensity ratio of H of the main chain bonded to the tertiary carbon of R)-). The estimation of the strength ratio of H in the main chain by ¹ H-NMR measurement is carried out with the fluorine-containing copolymer before hydroxylation.

The said fluorine-containing copolymer may have other monomer units other than a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ester monomer unit in the range which does not impair the effect of this invention.

As said other monomer, as a monomer which does not contain a fluorine atom (however, except vinyl alcohol and a vinyl ester monomer), for example, ethylene, propylene, 1-butene, 2-butene, vinyl chloride, Preference is given to at least one fluorine-free ethylenic monomer selected from the group consisting of vinylidene chloride, vinyl ether monomers and unsaturated carboxylic acids.

The total content of the other monomer units is preferably 0 to 50 mol%, more preferably 0 to 40 mol%, based on all monomer units of the fluorine-containing copolymer, More preferably, it is 30 mol%.

In the present specification, the content of each monomer unit constituting the fluorine-containing copolymer can be calculated by appropriately combining NMR, FT-IR, and elemental analysis depending on the type of monomer.

The weight average molecular weight of the fluorine-containing copolymer is not particularly limited, but is preferably 9,000 or more, and more preferably 10,000 or more. More preferably, it is 20,000-2,000,000, Most preferably, it is 30,000-1,000,000.
The weight average molecular weight can be determined by gel permeation chromatography (GPC).

As described later, the fluorine-containing copolymer can be produced by hydroxylating a copolymer having a fluorine-containing olefin unit and a vinyl ester monomer unit. That is, the fluorine-containing copolymer in the present invention is a copolymer obtained by hydroxylating a copolymer having a fluorine-containing olefin unit and a vinyl ester monomer unit. One.

Below, the manufacturing method of the fluorine-containing copolymer in this invention is demonstrated.
Usually, the fluorine-containing copolymer in the present invention is produced by copolymerizing a fluorine-containing olefin such as tetrafluoroethylene and a vinyl ester monomer such as vinyl acetate, and then hydroxylating the obtained copolymer. can do. As a method for polymerizing the fluorine-containing copolymer, it is preferable to carry out the polymerization under a condition in which the composition ratio of the fluorine-containing olefin and the vinyl ester monomer is kept substantially constant. That is, the above-mentioned fluorine-containing copolymer is polymerized under a condition in which the composition ratio of the fluorine-containing olefin and the vinyl ester monomer is kept almost constant to obtain a copolymer having a fluorine-containing olefin unit and a vinyl ester monomer unit. It is preferably obtained by a production method comprising a step and a step of obtaining a copolymer having a fluorine-containing olefin unit and a vinyl alcohol unit by hydroxylating the obtained copolymer.

Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl isovalerate, vinyl caproate, vinyl heptylate, vinyl caprylate, vinyl pivalate, pelargon. Vinyl acid, vinyl caprate, vinyl laurate, vinyl myristate, vinyl pentadecylate, vinyl palmitate, vinyl margarate, vinyl stearate, vinyl octylate, Veova-9 (manufactured by Showa Shell Sekiyu KK), Veova 10 (manufactured by Showa Shell Sekiyu KK), vinyl benzoate, vinyl versatate, and the like. Of these, vinyl acetate, vinyl propionate, and vinyl versatate are preferably used because they are easily available and inexpensive.
As said vinyl ester monomer, 1 type of these may be used and 2 or more types may be mixed and used.

Examples of the method of copolymerizing the fluorinated olefin and the vinyl ester monomer include solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like, and emulsion polymerization is easy because it is industrially easy to implement. However, it is preferable to produce by solution polymerization or suspension polymerization, but not limited thereto.

In emulsion polymerization, solution polymerization, or suspension polymerization, a polymerization initiator, a solvent, a chain transfer agent, a surfactant, a dispersant, and the like can be used, and those usually used can be used.

The solvent used in the solution polymerization is preferably a solvent capable of dissolving the fluorine-containing olefin, the vinyl ester monomer, and the fluorine-containing copolymer to be synthesized. For example, n-butyl acetate, t-butyl acetate, ethyl acetate Esters such as methyl acetate and propyl acetate; Ketones such as acetone, methyl ethyl ketone and cyclohexanone; Aliphatic hydrocarbons such as hexane, cyclohexane and octane; Aromatic hydrocarbons such as benzene, toluene and xylene; Methanol and ethanol Alcohols such as tert-butanol and isopropanol; cyclic ethers such as tetrahydrofuran and dioxane; fluorine-containing solvents such as HCFC-225; dimethyl sulfoxide, dimethylformamide, and mixtures thereof.
Examples of the solvent used in the emulsion polymerization include water, a mixed solvent of water and alcohol, and the like.

Examples of the polymerization initiator include oil-soluble radical polymerization initiators typified by peroxycarbonates such as diisopropyl peroxydicarbonate (IPP) and di-n-propyl peroxydicarbonate (NPP). Water-soluble radical polymerization initiators such as persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, ammonium percarbonate, potassium salt and sodium salt can be used. Particularly in emulsion polymerization, ammonium persulfate and potassium persulfate are preferred.

As the surfactant, a commonly used surfactant can be used. For example, a nonionic surfactant, an anionic surfactant, a cationic surfactant and the like can be used. Moreover, you may use a fluorine-containing surfactant.

Examples of the dispersant used in suspension polymerization include partially saponified polyvinyl acetate, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and other water-soluble cellulose ethers used in ordinary suspension polymerization, and acrylic acid polymers. And water-soluble polymers such as gelatin. The suspension polymerization is carried out under the condition that the water / monomer ratio is usually 1.5 / 1 to 3/1 by weight, and the dispersant is 0.01 to 0 with respect to 100 parts by weight of the monomer. 1 part by weight is used. If necessary, a pH buffer such as polyphosphate can be used.

Examples of the chain transfer agent include hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; and acetates such as ethyl acetate and butyl acetate; Examples include alcohols such as methanol and ethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, and methyl chloride.
The amount of the chain transfer agent added may vary depending on the size of the chain transfer constant of the compound used, but is usually used in the range of 0.001 to 10% by mass relative to the polymerization solvent.

The polymerization temperature may be in a range where the composition ratio during the reaction of the fluorinated olefin and the vinyl ester monomer is substantially constant, and may be 0 to 100 ° C.

The polymerization pressure may be in a range in which the composition ratio during the reaction of the fluorinated olefin and the vinyl ester monomer is substantially constant, and may be 0 to 10 MPaG.

Hydroxylation of an acetate group derived from vinyl acetate is well known in the art, and can be performed by a conventionally known method such as alcoholysis or hydrolysis using an acid or base. Among them, hydrolysis using a base is generally called saponification. In this specification, however, hydroxylation of a vinyl ester monomer is hereinafter called saponification regardless of the method. By this saponification, the acetate group (—OCOCH ₃ ) is converted into a hydroxyl group (—OH). Similarly, other vinyl ester monomers can be saponified by a conventionally known method to obtain a hydroxyl group.

The degree of saponification in the case of obtaining a fluorine-containing copolymer in the present invention by saponifying a copolymer having a fluorine-containing olefin unit and a vinyl ester monomer unit is the content of each monomer unit of the fluorine-containing copolymer in the present invention. It is sufficient that the rate is within the above-mentioned range, specifically, 50% or more is preferable, 60% or more is more preferable, and 70% or more is still more preferable.

The saponification degree is calculated from the following equation by IR measurement or ¹ H-NMR measurement of the fluorine-containing copolymer.
Saponification degree (%) = D / (D + E) × 100
D: number of vinyl alcohol units in the fluorinated copolymer E: number of vinyl ester monomer units in the fluorinated copolymer

The fluorine-containing copolymer in the present invention is a vinyl ether monomer (CH ₂ = CH-OR) (hereinafter simply referred to as a vinyl ether monomer) in which a fluorine-containing olefin and a protecting group (R) that can be converted to vinyl alcohol by deprotection reaction are bonded. And a fluorine-containing olefin / vinyl alcohol copolymer by deprotecting the fluorine-containing olefin / vinyl ether copolymer. It can obtain also by the manufacturing method which consists of a process of obtaining.

A method for copolymerizing the fluorinated olefin and the vinyl ether monomer and a method for deprotecting the fluorinated olefin / vinyl ether copolymer are well known in the art. It can be carried out. By deprotecting the fluorinated olefin / vinyl ether copolymer, the protecting group alkoxy group is converted to a hydroxyl group, and a fluorinated olefin / vinyl alcohol copolymer is obtained.

The fluorine-containing olefin / vinyl ether copolymer obtained by copolymerizing the fluorine-containing olefin and the vinyl ether monomer is a molar ratio of the fluorine-containing olefin and the vinyl ether monomer (fluorine-containing olefin) / (vinyl ether unit The (mer) is preferably (40-60) / (60-40), and more preferably (45-55) / (55-45). When the molar ratio is in the above range and the deprotection is in the range described later, a fluorinated copolymer in which the molar ratio of each polymer unit is in the above range can be produced.

The deprotection of the fluorinated olefin / vinyl ether copolymer is preferably performed so that the degree of deprotection is 1 to 100%, and more preferably 30 to 100%.

The degree of deprotection is determined by ¹ H-NMR, the integrated value of protons derived from an acetyl group (CH ₃ C (═O) O—) near 2.1 ppm before and after deprotection, and 0.8 to 1.8 ppm. It can be measured by quantifying the integral value of protons derived from the main chain methylene group (—CH ₂ —CH—).
¹ H-NMR: GEMINI-300 manufactured by Varian

The vinyl ether monomer preferably does not contain a fluorine atom. The vinyl ether monomer is not particularly limited as long as it is deprotected, but tertiary butyl vinyl ether is preferable from the viewpoint of availability.

When the said fluorine-containing copolymer has a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ether unit, it is preferable that the alternating rate of a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ether unit is 94% or less. When the alternating rate is in such a range, an effect that the obtained film is excellent in flexibility can be obtained. More preferably, it is 90% or less, and particularly preferably 80%. Further, it is preferably 30% or more, more preferably 35% or more, and further preferably 40%. If the alternating rate is low, the heat resistance is lowered, which is not preferable.

The alternating rate of the fluorinated olefin unit, the vinyl alcohol unit and the vinyl ether unit was measured by ¹ H-NMR measurement of the fluorinated copolymer using a solvent in which the fluorinated copolymer such as heavy acetone was dissolved. It can be calculated as an alternating rate of three chains from the equation.
Alternating rate (%) = C / (A + B + C) × 100
A: The number of V combined with two Vs such as -VVVV- B: The number of V combined with V and T as -VVT- C: -TV- Number of Vs bonded to two Ts such as T- (T: fluorine-containing olefin unit, V: vinyl alcohol unit or vinyl ether unit)
The number of V units of A, B, and C is the tertiary carbon of vinyl alcohol unit (—CH ₂ —CH (OH) —) and vinyl ether unit (—CH ₂ —CH (OR)) measured by ¹ H-NMR. It calculates from the intensity ratio of H of the main chain to couple | bond. The estimation of the strength ratio of H in the main chain by ¹ H-NMR measurement is carried out with the fluorine-containing copolymer before hydroxylation.

Examples of the method for copolymerizing the fluorine-containing olefin and the vinyl ether monomer include solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, and the like, which are industrially easy to implement. Although it is preferable to manufacture by emulsion polymerization, solution polymerization, or suspension polymerization, it is not this limitation.

In the above emulsion polymerization, solution polymerization or suspension polymerization, a polymerization initiator, a solvent, a chain transfer agent, a surfactant, a dispersant and the like can be used, and those usually used can be used.

The solvent used in the solution polymerization is preferably a solvent capable of dissolving the fluorine-containing olefin, the vinyl ether monomer, and the fluorine-containing copolymer to be synthesized. For example, n-butyl acetate, t-butyl acetate, Esters such as ethyl acetate, methyl acetate and propyl acetate; Ketones such as acetone, methyl ethyl ketone and cyclohexanone; Aliphatic hydrocarbons such as hexane, cyclohexane and octane; Aromatic hydrocarbons such as benzene, toluene and xylene; Methanol Alcohols such as ethanol, tert-butanol and isopropanol; cyclic ethers such as tetrahydrofuran and dioxane; fluorine-containing solvents such as HCFC-225; dimethyl sulfoxide, dimethylformamide, and mixtures thereof.
Examples of the solvent used in the emulsion polymerization include water, a mixed solvent of water and alcohol, and the like.

Examples of the polymerization initiator include oil-soluble radical polymerization initiators typified by peroxycarbonates such as diisopropyl peroxydicarbonate (IPP) and di-n-propyl peroxydicarbonate (NPP). Water-soluble radical polymerization initiators such as persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, ammonium percarbonate, potassium salt and sodium salt can be used. Particularly in emulsion polymerization, ammonium persulfate and potassium persulfate are preferred.

As the surfactant, a commonly used surfactant can be used. For example, a nonionic surfactant, an anionic surfactant, a cationic surfactant and the like can be used. Moreover, you may use a fluorine-containing surfactant.

Examples of the dispersant used in suspension polymerization include partially saponified polyvinyl acetate, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and other water-soluble cellulose ethers used in ordinary suspension polymerization, and acrylic acid polymers. And water-soluble polymers such as gelatin. The suspension polymerization is carried out under the condition that the water / monomer ratio is usually 1.5 / 1 to 3/1 by weight, and the dispersant is 0.01 to 0 with respect to 100 parts by weight of the monomer. 1 part by weight is used. If necessary, a pH buffer such as polyphosphate can be used.

Examples of the chain transfer agent include hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; and acetates such as ethyl acetate and butyl acetate; Examples include alcohols such as methanol and ethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, and methyl chloride.
The amount of the chain transfer agent added may vary depending on the size of the chain transfer constant of the compound used, but is usually used in the range of 0.001 to 10% by mass relative to the polymerization solvent.

The polymerization temperature may be in a range in which the composition ratio during the reaction of the fluorinated olefin and the vinyl ether monomer is substantially constant, and may be 0 to 100 ° C.

The polymerization pressure may be in a range where the composition ratio during the reaction of the fluorinated olefin and the vinyl ether monomer is substantially constant, and may be 0 to 10 MPaG.

The deprotection of the vinyl ether monomer can be performed by a conventionally known method such as acid, heat or light. By this deprotection, the leaving group (for example, —C (CH ₃ ) ₃ ) can be replaced with hydrogen to obtain a hydroxyl group.

The degree of deprotection in the case of obtaining the fluorine-containing copolymer in the present invention by deprotecting the copolymer having the above-mentioned fluorine-containing olefin unit and vinyl ether monomer unit is determined according to each monomer of the fluorine-containing copolymer in the present invention. The unit content may be in the range as described above, specifically 50% or more is preferable, 60% or more is more preferable, and 70% or more is still more preferable.

The degree of deprotection is calculated from the following formula by IR measurement of the fluorine-containing copolymer or the above-mentioned ¹ H-NMR measurement.
Deprotection degree (%) = D / (D + E) × 100
D: Number of vinyl alcohol units in the fluorinated copolymer E: Number of vinyl ether monomer units in the fluorinated copolymer

The agricultural film of the present invention may further contain components other than the above-mentioned fluorine-containing copolymer as long as the effects of the present invention are not impaired.

Examples of the other components include light stabilizers, antioxidants, lubricants, heat stabilizers, colorants such as pigments and dyes, antifoggants, and antistatic agents.

It is also preferred that the agricultural film of the present invention does not substantially contain an ultraviolet absorber. The film of the present invention is excellent in weather resistance even if it contains substantially no ultraviolet absorber. Therefore, ultraviolet rays are not shielded more than necessary, and the growth of crops that require ultraviolet rays and the flying performance of insects that contribute to pollination are improved.

Examples of the UV absorber include those known as UV absorbers, such as benzophenone UV absorbers, benzotriazole UV absorbers, salicylic acid ester UV absorbers, and cyanoacrylate UV absorbers. .

The phrase “substantially free of ultraviolet absorber” means that the ultraviolet absorber is 1% by mass or less with respect to 100% by mass of the film of the present invention.

The agricultural film of the present invention is produced by blending other components as necessary with the above-mentioned fluorine-containing copolymer, and molding by a known film molding method such as an extrusion molding method, a calendar molding method, or a solvent casting method. can do.

The thickness of the agricultural film of the present invention may be appropriately determined according to the required characteristics, but is preferably 10 to 1000 μm. More preferably, it is 20-500 micrometers, More preferably, it is 30-400 micrometers. If the thickness is too thin, the film tends to be torn, and if it is too thick, it is inconvenient for cutting, adhering, stretching, etc., and the light transmittance may be lowered.

The agricultural film of the present invention preferably has a haze value of 10% or less. More preferably, it is 7% or less, More preferably, it is 5% or less. Moreover, a minimum is not specifically limited, The lower one is preferable.

The agricultural film of the present invention preferably has a total light transmittance of 80% or more in the visible region. More preferably, it is 90% or more, More preferably, it is 93% or more.

In this specification, the haze value and the total light transmittance in the visible region are measured according to ASTM D1003 using a haze meter.

The agricultural film of the present invention preferably has an ultraviolet transmittance of 60% or more. More preferably, it is 65% or more, More preferably, it is 70% or more.
In this specification, the ultraviolet transmittance is a value obtained by measuring the total light transmittance at 380 nm using a spectrophotometer.

The present invention is also an agricultural covering material having the above-described film of the present invention and an antifogging agent layer made of an antifogging agent provided on at least one surface of the film.

Examples of the antifogging agent include surfactants effective as an antifogging agent, hydrophilic polymers, fine inorganic particles, or a mixture of two or more of these.

Examples of the surfactant include sorbitan fatty acid ester, sorbitol fatty acid ester, diglycerin fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid dibasic acid ester, sorbitol fatty acid dibasic acid ester, diglycerin fatty acid dibasic acid ester, glycerin fatty acid diester. Examples thereof include basic acid esters and compounds obtained by adding these to alkylene oxides such as ethylene oxide and propylene oxide.

Examples of the hydrophilic polymer include -SO ₄ , -SO ₃ H, -COOH, -NH ₂ , -CN,-(OCH ₂ CH ₂ ) _x- (here, in addition to polyvinyl alcohol, polyvinyl pyrrolidone and the like. And x is an integer of about 1 to 20, for example, and a polymer having a hydrophilic functional group.

Examples of the fine inorganic particles include silica, alumina, titanium oxide and the like.

As the antifogging agent, a surfactant, a hydrophilic polymer, or a fine particle inorganic substance alone is sufficiently effective, but a fine particle inorganic substance such as silica and alumina and a hydrophilic polymer such as polyvinyl alcohol and polyvinyl pyrrolidone are used. By using together, a further anti-fogging effect and a lasting effect are acquired.

The antifogging agent layer in the present invention is a layer made of an antifogging agent. The antifogging agent layer may be composed of only the antifogging agent, or may be composed of the antifogging agent and other components.

The antifogging agent layer preferably contains a binder as another component. Examples of the binder include (meth) acrylic acid ester resins and vinyl acetate resins.

The said anti-fogging agent layer can be formed by apply | coating the coating composition which added the other component as needed to the said anti-fogging agent to at least one surface of the film of this invention.

A solvent, an additive, and the like may be added to the coating composition for the purpose of improving workability and improving surface smoothness. As the solvent, for example, water, various alcohols, ketones, esters, ethers and the like can be appropriately used.

The coating composition can be applied to the film of the present invention by brush coating, roller coating, hand coating, spin coating, dip coating, coating by various printing methods, bar coating, curtain flow, die coating, flow coating, spraying. A coat etc. are mentioned. You may perform a well-known drying process as needed. In addition, for the purpose of increasing the mechanical strength of the coating film, heating or irradiation with ultraviolet rays or electron beams may be performed as necessary.

In the agricultural covering material of the present invention, it is preferable that the film of the present invention and the antifogging agent layer are directly bonded without interposing other layers. The other layer includes a surface treatment layer obtained by treating the surface of the film of the present invention with a surface treatment method such as plasma treatment or corona discharge treatment. Since the film of the present invention is excellent in affinity with the antifogging agent, the agricultural coating material of the present invention can be applied to the film of the present invention and the antifogging agent without performing surface treatment or providing an adhesive layer. Excellent adhesion to the layer.

The antifogging agent layer may be provided only on one side of the film of the present invention or may be directed on both sides. When provided on only one surface, a thermoplastic polymer layer, an antifouling film, an antistatic film, a heat insulating film, an ultraviolet cut film or the like can be provided on the other surface.

The thermoplastic polymer constituting the thermoplastic polymer layer may be any polymer other than the above-mentioned fluorine-containing copolymer that can be melt-molded, and examples thereof include polyolefin resins, polyesters, polycarbonates, and acrylic resins. In the case of providing a thermoplastic polymer layer, the fluorine-containing copolymer and the thermoplastic polymer are coextruded, or the film of the present invention is formed on a previously prepared thermoplastic polymer layer by a solvent casting method. After producing a laminate comprising the film of the present invention and a thermoplastic polymer layer, the antifogging agent layer may be formed on the surface of the film of the present invention opposite to the thermoplastic polymer layer.
An agricultural laminate comprising the film of the present invention and a thermoplastic polymer layer is also one aspect of the present invention.

From the viewpoint of cost reduction, the agricultural covering material of the present invention preferably comprises only the film of the present invention and the antifogging agent layer.

The thickness of the antifogging agent layer is preferably 0.01 to 50 μm. More preferably, it is 0.05-20 micrometers, More preferably, it is 0.1-10 micrometers. If it is too thin, the hydrophilicity and sustainability of the effect may be reduced. If it is too thick, cracks may easily occur, interference fringes may occur, and scratches may become noticeable. There is.

It is also preferred that the agricultural coating material of the present invention does not substantially contain an ultraviolet absorber. The agricultural coating material of the present invention is excellent in weather resistance even if it does not substantially contain an ultraviolet absorber. Therefore, ultraviolet rays are not shielded more than necessary, and the growth of crops that require ultraviolet rays and the flying performance of insects that contribute to pollination are improved. The ultraviolet absorber is as described above.

The phrase “substantially free of UV absorber” means that the UV absorber is 1% by mass or less with respect to 100% by mass of the agricultural coating material of the present invention.

The agricultural coating material of the present invention preferably has a haze value of 10% or less. More preferably, it is 7% or less, More preferably, it is 5% or less. Moreover, a minimum is not specifically limited, The lower one is preferable.

The agricultural covering material of the present invention preferably has a total light transmittance of 80% or more in the visible region. More preferably, it is 90% or more, More preferably, it is 93% or more.

The agricultural coating material of the present invention preferably has an ultraviolet transmittance of 60% or more. More preferably, it is 65% or more, More preferably, it is 70% or more.

Since the agricultural covering material of the present invention is excellent in interlayer adhesion, transparency, ultraviolet light transmittance and weather resistance, it is suitable for agricultural and horticultural facilities such as tunnel houses, pipe houses, large houses for the cultivation of farm products. be able to. In this case, it is preferable that the antifogging agent layer is applied so as to be inside the house.

Next, the present invention will be described with reference to examples. However, the present invention is not limited to such examples.

Each numerical value of the examples was measured by the following method.

[Measurement of composition and alternating rate of fluoropolymer by NMR (nuclear magnetic resonance method)]
^{For the 1} H-NMR (nuclear magnetic resonance method) measurement, JNM-EX270 (manufactured by JEOL: 270 MHz) was used. Heavy acetone was used as the solvent.

[Molecular weight and molecular weight distribution]
By gel permeation chromatography (GPC), using Tosoh's GPC HLC-8020, Shodex columns (one GPC KF-801, one GPC KF-802, GPC KF-806M) The average molecular weight was calculated from data measured by flowing tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min.
When the sample did not dissolve in THF, the average molecular weight was calculated by the following method. A high-performance liquid chromatograph manufactured by JASCO Corporation was used, and the analysis column set was one guard column (Shodex GPC KD-G [4.6 mm ID × 10 mm L]) and an analysis column (KD-806M [8. 0 mm ID × 300 mm L] 3 were used, N-methyl-2-pyrrolidone containing 10 mM LiBr as a mobile solvent, RI as a detector, a polystyrene standard sample as a calibration curve sample, and a flow rate of 1 ml. Measurement was performed at a sample injection amount of 200 μL / min, and a data station (ChromNAV) was used for data analysis.

[Glass transition temperature (Tg)]
Using DSC (Differential Scanning Calorimeter: RTG220, manufactured by SEIKO), the temperature range from −50 ° C. to 200 ° C. was raised at a rate of 10 ° C./min (first run) -temperature fall-temperature rise (second run) The intermediate point of the endothermic curve in the second run was defined as Tg (° C.).

[Melting point (Tm)]
Using DSC (Differential Scanning Calorimeter: RTG220, manufactured by SEIKO), the temperature was increased (first run) -temperature-lowered (second run) at 10 ° C./min, and the maximum value in the heat of fusion curve in the second run. The temperature corresponding to is Tm (° C.).

[IR analysis]
The measurement was performed at room temperature using a Perkin Elmer Fourier transform infrared spectrophotometer 1760X.

[Fluorine content]
By burning 10 mg of sample by the oxygen flask combustion method, absorbing the decomposition gas in 20 ml of deionized water, and measuring the fluorine ion concentration in the absorption liquid by the fluorine selective electrode method (fluorine ion meter, model 901 manufactured by Orion) Determined (mass%).

Synthesis example 1
In a 2.5 L stainless steel autoclave, 980 g of butyl acetate as a solvent and 17 g of vinyl acetate as a vinyl ester monomer are added, 6.2 g of perbutyl PV (product name, manufactured by NOF Corporation) is added as a polymerization initiator, and a flange is formed. The autoclave was replaced with vacuum and the bath temperature was raised to 60 ° C. With stirring, 93 g of tetrafluoroethylene was sealed as a fluorine olefin gas to start the reaction. At this time, the pressure in the tank was 0.74 MPa, and the stirring speed was 200 rpm.
Addition of vinyl acetate was started at the start of the reaction, and 93 g of vinyl acetate was added over 4 hours. During the reaction, tetrafluoroethylene was continuously supplied using a solenoid valve so that the ratio of vinyl acetate / tetrafluoroethylene was constant. The stirring speed was 200 rpm.

Specifically, when tetrafluoroethylene is consumed and the inside of the tank reaches 0.720 MPa, the solenoid valve is automatically opened to supply tetrafluoroethylene, and when 0.740 MPa is reached, the solenoid valve is automatically closed and tetrafluoroethylene is closed. While controlling the supply and pressure of tetrafluoroethylene in a cycle in which the supply of ethylene was stopped, vinyl acetate was added in accordance with the consumption of tetrafluoroethylene.

Four hours after the start of the reaction, the supply of tetrafluoroethylene and vinyl acetate was stopped. Thereafter, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and 1110 g of a butyl acetate solution of vinyl acetate / tetrafluoroethylene copolymer (solid content concentration 21.0% by mass) was obtained.
After completion of the reaction, the polymer solution was reprecipitated in a large amount of methanol solution, and the polymer was purified to obtain polymer A1.

The composition of the polymer A1 was determined from elemental analysis of fluorine, the alternating ratio of fluorine olefin and vinyl ester was calculated from ¹ H-NMR, and the weight average molecular weight and molecular weight distribution (Mw / Mn) were determined from GPC. The glass transition temperature was measured from DSC. The results are shown in Table 2.

Synthesis example 2
A 3 L stainless steel autoclave was charged with 1000 g of pure water, 23.2 g of vinyl acetate, Neocor P (76.4 mass% isopropyl alcohol solution of sodium dioctylsulfosuccinate: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), nitrogen-substituted, and tetrafluoro Ethylene 37g was added and the inside of a tank was heated up to 80 degreeC. Thereafter, 30 g of tetrafluoroethylene was added. At this time, the pressure in the tank was 0.809 MPa. Under stirring, 22 g of a 1% by mass aqueous solution of ammonium persulfate (APS) was added to initiate the reaction. The addition of vinyl acetate was started at the start of the reaction, and 283 g of vinyl acetate was added over 6 hours. During the reaction, tetrafluoroethylene was continuously supplied using a solenoid valve so that the ratio of vinyl acetate / tetrafluoroethylene was constant. The stirring speed was 500 rpm.

Specifically, when tetrafluoroethylene is consumed and the inside of the tank reaches 0.775 MPa, the solenoid valve is automatically opened to supply tetrafluoroethylene, and when 0.800 MPa is reached, the solenoid valve is automatically closed and tetrafluoroethylene is closed. While controlling the supply and pressure of tetrafluoroethylene in a cycle in which the supply of ethylene was stopped, vinyl acetate was added in accordance with the consumption of tetrafluoroethylene.

Six hours after the start of the reaction, the supply of tetrafluoroethylene and vinyl acetate was stopped. Then, after reacting for 1 hour, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, thereby obtaining 1661 g of a vinyl acetate / tetrafluoroethylene copolymer emulsion (solid content concentration 38.5% by mass).

The resulting vinyl acetate / tetrafluoroethylene copolymer (Polymer A2) had a glass transition temperature of 40 ° C. and a particle size of 116 nm. The particle size was measured using a laser light scattering particle size measuring device (manufactured by Otsuka Electronics Co., Ltd., trade name ELS-3000).

Synthesis example 3
Into a 3 L stainless steel autoclave, 1200 g of butyl acetate as a solvent and 140 g of vinyl acetate as a vinyl ester monomer were added, 7.2 g of perbutyl PV (product name, manufactured by NOF Corporation) was added as a polymerization initiator, and the flange was tightened. The autoclave was replaced with vacuum, and the bath temperature was raised to 60 ° C. Under stirring, tetrafluoroethylene was sealed as a fluorine olefin gas to initiate the reaction. At this time, the pressure in the tank was 1.00 MPa, and the stirring speed was 500 rpm. Since the polymerization pressure was lowered, the consumption of the gas monomer was confirmed. In 6 hours, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and the remaining gas was blown to complete the reaction.

After completion of the reaction, the polymer solution was reprecipitated in a large amount of methanol solution, and the polymer was purified to obtain polymer A3.

The composition of polymer A3 was determined from elemental analysis of fluorine, the alternating ratio of fluorine olefin and vinyl ester was calculated from ¹ H-NMR, and the weight average molecular weight and molecular weight distribution (Mw / Mn) were determined from GPC. The glass transition temperature was measured from DSC. The results are shown in Table 2.

Synthesis example 4
A 300 mL stainless steel autoclave is charged with 50 g of butyl acetate solvent and 10 g of vinyl stearate monomer, 0.4 g of perbutyl PV (product name, manufactured by NOF Corporation) is added as a polymerization initiator, the flange is tightened, and the autoclave is vacuum-substituted. Then, 8.0 g of tetrafluoroethylene was encapsulated as a fluorine olefin gas, and 2.6 g of hexafluoropropylene was subsequently encapsulated, and the mixture was placed in a shaking thermostat at 60 ° C. to initiate the reaction. Since the polymerization pressure was lowered, the consumption of the gas monomer was confirmed, the shaking was stopped in 15 hours, and the remaining gas was blown to complete the reaction.

After completion of the reaction, the polymer solution was reprecipitated in a large amount of methanol solution, and the polymer was purified to obtain polymer B1.

The same analysis as in Synthesis Example 1 was performed except that the melting point was measured instead of the glass transition temperature. The results are shown in Table 2.

Synthesis example 5
In a 300 mL stainless steel autoclave, 50 g of butyl acetate as a solvent and 10 g of vinyl acetate as a vinyl ester monomer were added, 0.4 g of perbutyl PV (product name, manufactured by NOF Corporation) was added as a polymerization initiator, and the flange was tightened. The autoclave was vacuum-replaced, 17 g of chlorotrifluoroethylene was sealed as a fluorine olefin gas, and the reaction was started by placing it in a shaking thermostat at 60 ° C. Since the polymerization pressure was lowered, the consumption of the gas monomer was confirmed, the shaking was stopped in 4 hours, the remaining gas was blown to terminate the reaction, and polymer B2 was obtained. The reaction conditions are summarized in Table 1, and the physical properties of the obtained polymer are summarized in Table 2.

Synthesis Example 6
(Synthesis of t-butyl vinyl ether / tetrafluoroethylene copolymer)
A 300 ml stainless steel autoclave is charged with 150 g of t-butanol, 26.7 g of t-butyl vinyl ether and 0.48 g of potassium carbonate, 0.46 g of a 70% isooctane solution of perbutyl PV as a catalyst is added, the flange is tightened, and the autoclave is vacuum-substituted. Then, 26.7 g of tetrafluoroethylene was sealed, and the reaction was started by placing it in a 60 ° C. shaking thermostat. Since the polymerization pressure was lowered, the consumption of the gas monomer was confirmed, the shaking was stopped in 3 hours, and the remaining gas was blown to complete the reaction.
After completion of the reaction, the polymer solution was reprecipitated in a large amount of methanol solution, and the polymer was purified to obtain a t-butyl vinyl ether / tetrafluoroethylene copolymer (polymer C1). The composition of the t-butyl vinyl ether / tetrafluoroethylene copolymer determined by elemental analysis of fluorine was 52/48 (molar ratio). The reaction conditions are summarized in Table 1, and the physical properties of the obtained polymer are summarized in Table 2.

Synthesis example 7 (saponification homogeneous system)
The TFE / vinyl acetate polymer A3 obtained in Synthesis Example 3 was uniformly dissolved in a 50 g THF solvent so as to have a concentration of 10% by mass. Thereafter, a 0.6N NaOH solution was added to give an equivalent amount of vinyl acetate in the polymer, and after 30 minutes the polymer was reprecipitated in a large amount of water. After washing with 1N HCl, it was thoroughly washed with ion-exchanged water, and the reprecipitated polymer was suction filtered and dried at 80 ° C. for 2 hours with a dryer. As a result of calculating the hydrolysis rate (degree of saponification) from the relative intensity of the carbonyl peak by IR, 34% of TFE / vinyl alcohol / vinyl acetate polymer A3-34 was obtained. The results are summarized in Table 3.

Synthesis examples 8 to 10 (saponification homogeneous system)
By changing the saponification time of Synthesis Example 7, AFE-vinyl alcohol / vinyl acetate polymers A3-45, A3-86, and A3-96 were obtained. The results are summarized in Table 3.

Synthesis Examples 11 to 13 (saponification uniform system)
A saponification polymer, A1-98, B1-97 and Synthesis Example 7 were used in the same manner as in Synthesis Example 7, except that the saponification time of Synthesis Example 7 was 1 day and the polymers obtained in Synthesis Example 1 and Synthesis Examples 4-5 were used. B2-96 was obtained. The results are summarized in Table 3.

Synthesis Example 14
The emulsion of vinyl acetate / tetrafluoroethylene copolymer obtained in Synthesis Example 2 was freeze-coagulated, rinsed with pure water, and then dried. The TFE / vinyl acetate polymer (Polymer A2) had a concentration of 10 in 50 g THF solvent. It was uniformly dissolved so as to be mass%. After that, 0.6N NaOH solution was added so as to be equivalent to vinyl acetate in the polymer, neutralized with 1N HCl after stirring for 24 hours, re-precipitated in a large amount of pure water, washed well with ion-exchanged water, The reprecipitated polymer was suction filtered and dried at 80 ° C. for 2 hours with a dryer. As a result of calculating the hydrolysis rate from the relative intensity of the carbonyl peak by IR, 96% TFE / vinyl alcohol / vinyl acetate polymer (A2-96) was obtained. The results are summarized in Table 3.

Synthesis Example 15 (Deprotection Step)
(Hydrolysis: Synthesis of vinyl alcohol / tetrafluoroethylene copolymer)
In a 100 ml eggplant flask, 5.26 g of t-butyl vinyl ether / tetrafluoroethylene copolymer obtained in Synthesis Example 6 (t-butyl vinyl ether / tetrafluoroethylene = 52/48 (molar ratio)), 1,4-dioxane 2 4 ml, 4N HCl aqueous solution 100 ml was added and heated and stirred at 80 ° C. After 2 hours, heating was stopped and the mixture was allowed to cool, and the precipitated polymer was washed 3 times with pure water. The polymer was dissolved in tetrahydrofuran (THF), reprecipitated in a solution of ethanol / water (50/50% by volume), and dried in vacuo to obtain a purified vinyl alcohol / tetrafluoroethylene copolymer (C1-95). ). The degree of deprotection was 95%. The results are summarized in Table 3.

Example 1
The polymer (A3-34) obtained in Synthesis Example 7 was dissolved in a butyl acetate solution so as to be 40% by mass. Then, it apply | coated to the Suntec ^TM- EVA film EF1531 by Asahi Kasei Chemicals which is a polyolefin resin film for agriculture using a bar coat (# 10). After preliminary drying at room temperature for 30 minutes, the film was dried at 120 ° C. for 30 minutes in a blower dryer. It was 25 micrometers as a result of measuring the film thickness after drying with a micrometer.
The obtained coating film was evaluated for the following items. The evaluation results are shown in Table 4.

(Cross-cut adhesion test)
Evaluation was performed by a cross-celling cellophane tape peeling test of JIS K5600. The coating film is cut with a grid knife at intervals of 1 mm with a cutter knife, peeled after attaching a cellophane tape, 10 points with no peeled part, 8 points with more than 0% and less than 5%, 5 points % And less than 15% were evaluated as 6 points, 15% and less than 35% as 4 points, 35% and less than 65% as 2 points, and 65% or more as 0 points.

(Measurement of haze and total light transmittance)
The haze value and total light transmittance were measured according to ASTM D1003 using a haze meter (Hazeguard II manufactured by Toyo Seiki Co., Ltd.).

Examples 2-9
The same as Example 1 except that the polymers A3-45, A3-86, A3-96, A1-98, B1-97, B2-96, A2-96, C1-95 were used instead of the polymer A3-34. Then, a coating film was formed on the agricultural polyolefin resin film, and various physical properties were measured. The film thickness after drying was 25 μm in all cases. The results are shown in Table 5.

Example 10
Polymer A2-96 obtained in Synthesis Example 14 was dissolved in a butyl acetate solution so as to be 40% by mass. Then, a self-supporting film having a thickness of 400 μm was obtained by casting. The haze value and total light transmittance of the obtained film were measured in the same manner as in Example 1. Further, the ultraviolet transmittance was also measured by the following method. The results are shown in Table 6.

(Measurement of UV transmittance)
Using a spectrophotometer (Spectrophotometer U-4100 manufactured by Hitachi, Ltd.), the wavelength was measured at 380 nm.

Example 11 (accelerated weather resistance)
As a result of conducting the following accelerated weather resistance test on the film obtained in Example 10, the evaluation was A.

(Accelerated weather resistance test)
An accelerated weather resistance test was conducted for 500 hours with an ice par UV tester W-13 type manufactured by Iwasaki Electric Co., Ltd. (Light / Dew / Rest = 11/11 / 1HR as one cycle), and the appearance was visually observed. . Evaluation is performed according to the following criteria.
A: No abnormality B: Some discoloration C: Significant discoloration

Example 12 (direct application of anti-fogging agent and adhesion evaluation)
Isopropyl alcohol was added to silica sol (manufactured by Nissan Chemical Industries, trade name: Snowtex IPA-ST, primary particle size 10 to 20 nm) to dilute to a solid content concentration of 6% by mass. After applying to the film obtained in Example 10 with a bar coater, it was dried at 80 ° C. for 10 minutes to form a 0.3 μm coating film (antifogging agent layer) to obtain a sample in which an antifogging agent layer was formed. It was.
About the obtained sample, while performing the cross-cut adhesion test by said method, the total light transmittance and haze were measured. Further, the contact angle with water was measured by the following method. The results are shown in Table 7. The cross-cut adhesion test and the water contact angle were measured on the surface of the antifogging agent layer.

(Water contact angle)
It measured using the contact angle meter (CA-DT * A type | mold by Kyowa Interface Science Co., Ltd.).

Comparative Example 1
A sample in which an antifogging agent layer was formed was obtained in the same manner as in Example 12 except that a 25 μm ETFE film (EP025 manufactured by Daikin Industries, Ltd.) was used instead of the film obtained in Example 10. Various physical properties were measured and evaluated in the same manner as in Example 12. The results are shown in Table 7.

Claims (7)

An agricultural film comprising a fluorine-containing copolymer having a fluorine-containing olefin unit and a vinyl alcohol unit. The agricultural film according to claim 1, wherein the fluorine-containing olefin is tetrafluoroethylene. The agricultural film according to claim 1 or 2, wherein a content of the fluorine-containing olefin unit in the fluorine-containing copolymer is 40 mol% or more. The agricultural film according to claim 1, 2, or 3, wherein an alternating rate of the fluorine-containing olefin unit and the vinyl alcohol unit in the fluorine-containing copolymer is 94% or less. The agricultural film according to claim 1, wherein the fluorine-containing copolymer has a fluorine-containing olefin unit, a vinyl alcohol unit, and a vinyl ester monomer unit. The agricultural film according to claim 1, wherein the fluorine-containing copolymer is a copolymer obtained by hydroxylating a copolymer having a fluorine-containing olefin unit and a vinyl ester monomer unit. . An agricultural covering material comprising the film according to claim 1, 2, 3, 4, 5 or 6, and an antifogging agent layer made of an antifogging agent provided on at least one surface of the film.