JP3224865B2 - Agricultural coating film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated film and a method for producing the same, and more particularly to an agricultural coated film and a method for producing the same.

[0002]

2. Description of the Related Art Fluororesin films have been used as agricultural covering films for greenhouses such as greenhouses for plant cultivation and tunnel houses (see, for example, JP-A-64-43535). However, a green house using a fluororesin film has an inactive surface, so that water droplets easily adhere to the inner surface. Water droplets adhering to the greenhouse adhere to the cultivated plants when the sunlight is blocked or dripped, which hinders the successful growth of the plants.

[0003] Therefore, various agricultural fluororesin films having an anti-fog function and to which water droplets are difficult to adhere have been provided. For example, Japanese Patent Application Laid-Open No. 62-179938 discloses an agricultural fluororesin film coated with an antifogging agent containing a layered silicate and a silane coupling agent. Further, Japanese Patent Application Laid-Open No. HEI 1-123737 discloses a particulate silica,
An agricultural fluororesin film coated with an antifogging agent containing at least one selected from alumina and titanium oxide is shown.

[0004]

The agricultural fluororesin film having antifogging property has good durability of the film, but has a short duration of antifogging property as compared with the service life of the film. Therefore, the conventional agricultural fluororesin film has a low antifogging property when used for a long period of time. It causes the same problem.

An object of the first and second aspects of the invention is to provide an agricultural covering film having good durability and good antifogging property for a long period of time. An object of the third invention is to provide a production method for efficiently producing an agricultural covering film having good durability and good antifogging property for a long period of time.

[0006]

The agricultural covering film according to the first invention comprises a fluororesin film layer having specific surface characteristics, and an antifogging agent layer disposed on the fluororesin film layer. . The anti-fogging agent layer contains an inorganic hydrophilic colloid substance, a surfactant, and a lithium silicate and / or silane derivative.

[0007] The agricultural coating film according to the second invention comprises:
A fluororesin film layer having a specific surface property, an underlayer formed on the fluororesin film layer and made of an organic compound having an atomic group containing oxygen and / or nitrogen, and an inorganic hydrophilic layer formed on the underlayer. An antifogging agent layer containing a colloidal substance, a surfactant, and a lithium silicate and / or silane derivative is provided.

[0008] The method for producing an agricultural covering film according to the third invention includes the following steps. ◎ Process of preparing a fluororesin film. ◎ Process of providing a surface treatment surface on a fluororesin film. A step of applying an antifogging agent containing an inorganic hydrophilic colloid substance, a surfactant, and a lithium silicate and / or a silane derivative to the surface-treated surface.

**** Fluororesin film layer The fluororesin film layer constituting the agricultural covering film of the present invention is composed of a polymer compound containing fluorine in its molecular structure. A general fluororesin is a polymer containing the following repeating unit (1).

[0010]

Embedded image Wherein X ₁ , X ₂ and X ₃ are H, Cl, F, -R _f ,
It is selected substituents from among -O-R _f. Also,
R _f is a perfluoroalkyl group containing 1 to 12 carbon atoms.

The following are specific examples of the fluororesin constituting the fluororesin film layer. Copolymer resin of tetrafluoroethylene and hexafluoropropylene.

Particularly, a copolymer resin composed of 95 to 50% by weight of tetrafluoroethylene and 5 to 50% by weight of hexafluoropropylene is preferable. Copolymer resin of chlorotrifluoroethylene and ethylene. Copolymer resin of tetrafluoroethylene and ethylene.

In particular, a copolymer resin composed of 40 to 60 mol% of tetrafluoroethylene and 40 to 60 mol% of ethylene is preferable. In this copolymer resin, if necessary, perfluoroalkylvinyl may be copolymerized as the third component. Perfluoroalkyl vinyl is represented by the following general formula (2). Where n is
It is an integer of 2 to 10.

[0014]

Embedded image Preferred as the copolymer resin containing perfluoroalkyl vinyl as the third component are 45 to 65 mol% of tetrafluoroethylene, 35 to 55 mol% of ethylene, and 0.1 to 10 mol% of perfluoroalkyl. It is a copolymer resin containing vinyl. Copolymer resin of tetrafluoroethylene and perfluoroalkyl vinyl ether.

Particularly, a copolymer resin containing 50 to 95% by weight of tetrafluoroethylene and 5 to 50% by weight of perfluoropropyl vinyl ether is preferable. Polyvinylidene fluoride resin. Polyvinyl fluoride resin.

The fluororesin film layer used in the present invention is obtained by forming the above-mentioned fluororesin into a film by, for example, an extrusion molding method or an inflation molding method.
The thickness of the fluororesin film layer is generally from 25 to 750.
μm, preferably 35 to 350 μm. When the thickness is less than 25 μm, the agricultural covering film according to the present invention is easily broken. On the other hand, if the thickness exceeds 750 μm, the workability such as cutting, bonding and spreading is reduced, and it is uneconomical.

Incidentally, a coloring agent may be added to the fluororesin film layer as needed. Examples of the coloring agent include titanium oxide, zinc white, calcium carbonate, precipitated silica, carbon black, chrome yellow, phthalocyanine blue, and phthalocyanine green.

The fluororesin film layer is subjected to a surface treatment on the surface anti-fogging agent layer is disposed, the wetting tension of the fill arm surface
It needs to be 30 dyne / cm or more. Film table
When the surface wetting tension is 30 dyne / cm or more,
Anchor effect appears on the surface, and the fluororesin film layer
Layer or antifogging agent layer is improved,
The continuity is improved. 30 dyn wet tension on the film surface
If it is less than e / cm, the antifogging performance and its durability are poor.
It becomes

Examples of the surface treatment include a chemical treatment and a discharge treatment. Chemical treatment is a surface treatment method in which a fluororesin film is immersed in an ammonia solution of metallic sodium or a tetrahydrofuran solution of sodium / naphthalene complex. On the other hand, the discharge treatment is a treatment method in which corona discharge, glow discharge (plasma treatment), sputter etching, and the like are performed on the surface of the fluororesin film, and high-energy particles collide with the film surface.

On the surface of the fluororesin film after the surface treatment, the number of fluorine atoms (F) with respect to the number of carbon atoms (C)
Is 0.8 to 1.8, and the relationship between the ratio (O / C) of the number of oxygen atoms (O) to the number of carbon atoms (O / C) and the above-mentioned F / C is the following relational expression. The F / C value of the portion other than the surface layer that satisfies (1) and is further subjected to the surface treatment is 1.9 to 2.
Preferably, it is set to zero.

[0021]

(Equation 1) Underlayer An underlayer may be formed on the above-mentioned fluororesin film layer if necessary .

The underlayer is made of an organic compound having an atomic group containing oxygen and / or nitrogen. Examples of atomic groups containing oxygen and / or nitrogen include amino groups, imino groups, carboxyl groups, hydroxyl groups, carbonyl groups, ether groups, epoxy groups, isocyanate groups, amide groups, urethane groups, ester groups, urea groups, cyano groups, and the like. Can be exemplified. Organic compounds having such an atomic group include polyurethane resins,
Examples thereof include a polyester resin, an epoxy resin, an acrylic resin, and polyvinyl alcohol.

The thickness of the underlayer is 0.01 to 1.0 μm,
Preferably, it is set to 0.05 to 0.5 μm. When such a base layer is provided on the fluororesin film layer, the effect of maintaining the antifogging property is further improved . Fogging agents used in the anti-fogging agent layer constituting an agricultural covering film of the anti-fogging agent layer present invention, an inorganic hydrophilic colloidal substance comprises a surfactant, and a lithium silicate and / or silane derivatives . Inorganic hydrophilic colloidal substances used in this antifogging agent include colloidal silica, colloidal alumina, colloidal Fe (OH) ₂ , colloidal Sn
(OH) ₄ , colloidal TiO ₂ , colloidal Ba
Examples include SO ₄ and colloidal lithium silicate. These colloidal substances may be used in combination of two or more. In particular, colloidal silica or colloidal alumina is particularly preferable as the inorganic hydrophilic colloid substance. The above-mentioned colloidal substance is preferably of an aqueous sol type.

The surfactant used in the antifogging agent may be any of an anionic surfactant, a nonionic surfactant, a cationic surfactant and an amphoteric surfactant. However, it is preferable that the surfactant is appropriately selected in relation to the above-mentioned inorganic hydrophilic colloid. For example, when colloidal silica is used, it is preferable to use an anionic surfactant and / or a nonionic surfactant. When colloidal alumina is used, it is preferable to use a cationic surfactant and / or a nonionic surfactant.

The lithium silicate used as the antifogging agent is obtained by melting silicon dioxide and a lithium salt such as lithium carbonate, and is represented by the following general formula (3).

[0026]

Embedded image Note that lithium silicates having different water solubility can be obtained depending on the mixing ratio of silicon dioxide and lithium salt. For example, those having n of 6 to 10 in the general formula are insoluble in water. Therefore, in this case, the lithium silicate
Since it can be colloidal, it can also be used as the above-mentioned inorganic hydrophilic colloid substance. On the other hand, since lithium silicate having n of 2 to 5 is water-soluble, it can be used together with the above-mentioned inorganic hydrophilic colloid substance as a binder.

The silane derivative contained in the antifogging agent is represented by the following general formula (4).

[0028]

Embedded image In the formula, R ₁ represents at least one reactive group selected from an amino group, an epoxy group, an epoxy group-containing group, a ureide group, an ammonium group and an ethylenically unsaturated bond-containing group.
Alkyl group or aryl group. Also, R ₂
And R ₃ each represent an alkyl group having 1 to 3 carbon atoms, and R ₂ and R ₃ may be the same or different. Furthermore, n has shown the integer of 1-3.

The antifogging agent contains an inorganic hydrophilic colloid substance in an amount of 80% by weight or more and 94.5% by weight or less, and a surfactant in an amount of 0.1% by weight.
It is preferable that the composition contains 5% by weight or more and 15% by weight or less and 5% by weight or more and 19.5% by weight or less of a lithium silicate and / or a silane derivative and is dispersed in water and / or alcohol.

The most preferred antifogging agents are colloidal silica, an ether type nonionic surfactant, R1 is an epoxy group or an alkyl group having at least one epoxy group-containing group, and R2 and R3 are carbon atoms. Is 1-3
And an alcohol having 1 to 4 carbon atoms, which contains the above-mentioned silane derivative which is an alkyl group. Manufacturing method of agricultural covering film First, a fluororesin film is prepared. As described above, the fluororesin film is obtained by extrusion molding or inflation molding from the above-described fluororesin. At this time, the thickness of the fluororesin film is 25 to 750 μm,
Preferably, it is set to 35 to 350 μm. When the fluororesin film is colored, the above-mentioned coloring agent is added to the fluororesin before molding.

Next, the fluororesin film is subjected to a surface treatment .
And the film surface has a wetting tension of 30 dyne / cm or more.
And As the surface treatment method, the above-mentioned chemical treatment and discharge treatment can be adopted. When corona discharge treatment is adopted as the discharge treatment method, the discharge treatment is performed by air, oxygen, nitrogen,
It may be carried out in any atmosphere of carbon dioxide, low molecular weight organic compounds and mixtures thereof. When the glow discharge treatment is adopted, the treatment may be performed in any of low pressure and normal pressure atmospheres. In this case, as the plasma gas, oxygen, nitrogen, helium, carbon dioxide, ammonia,
Low molecular organic compounds and mixed gases thereof can be used.
Note that a low-temperature plasma treatment is particularly preferable as the glow discharge treatment. According to the low-temperature plasma treatment, only the surface layer portion of the film can be modified without impairing the intrinsic properties of the fluororesin .

When performing the discharge treatment, the type of treatment can be appropriately selected according to the type of the fluororesin film. For example,
In the case of a fluororesin film having a high degree of fluorine substitution, such as a copolymer resin containing tetrafluoroethylene or hexafluoropropylene, a plasma treatment or a sputter etching treatment is preferable. In particular, a discharge treatment in a gas atmosphere of a low-molecular compound (for example, see Japanese Patent Publication No. 37-17485, Japanese Patent Publication No. 37-17682, and Japanese Patent Publication No. 49-12900) is preferable. In the case where the plasma treatment is performed, the adhesiveness is hardly reduced even when irradiated with ultraviolet light under high humidity.

The treatment conditions in the case of the discharge treatment are the composition,
In addition to gas atmosphere conditions such as concentration, pressure, and temperature, electric energy at the time of discharge is the main condition. Electrical energy is the amount of energy given to the film passing between the electrodes. min / m ² . The preferred amount of electric energy at the time of the treatment varies depending on the type of discharge, the gas atmosphere, the chemical structure of the fluororesin constituting the film, and the like. min / m ² or more, and in the case of plasma treatment, (5 / hydrogen substitution coefficient of fluororesin). min
/ M ² or more. Here, the hydrogen substitution coefficient of the fluororesin is a ratio of hydrogen atoms bonded to the carbon skeleton of the fluororesin, and is obtained by the following equation (2).

[0034]

(Equation 2) Specific examples of the hydrogen substitution coefficient of the fluororesin are as follows. Copolymer resin of tetrafluoroethylene and hexafluoropropylene (degree of hydrogen substitution: 0): 0.1 Copolymer resin of tetrafluoroethylene and ethylene (a copolymer having a monomer number ratio of 1: 1 and hydrogen substitution) Degree: 0.
5): 0.6 polyvinylidene fluoride (degree of hydrogen substitution: 0.5):
6 polyvinyl fluoride (degree of hydrogen substitution: 0.75): 0.8
5. The discharge voltage during the discharge treatment is preferably set to 1 KV or more. When the discharge voltage is 1 KV or less, the anti-fogging property of the anti-fogging agent layer is difficult to maintain for a long time, and the anti-fogging property tends to be uneven.

The wetting tension after the surface treatment is 30 dyne /
cm or more is required . The wetting tension is JIS-K
6768. An underlayer is formed on the above-mentioned surface-treated surface as needed. The underlayer can be formed by applying the above resin on the fluororesin film layer. Also,
It can also be formed by applying a prepolymer of the above-mentioned resin or a mixture of the prepolymer and the monomer, and subjecting this to a heat treatment or an electromagnetic wave irradiation treatment to polymerize the resin.

Next, an antifogging agent is applied on the surface-treated surface or the underlayer formed on the fluororesin film. The concentration of the antifogging agent is usually 0.1 to 20% by weight, preferably 0.5 to 1% by weight.
Set to 0% by weight. The anti-fogging agent is applied by a spray or a coater. At this time, the coating amount is set to ² g / m ² or less. If the coating amount is more than ² g / m ² , the anti-fogging property and the durability of the anti-fogging property are reduced.

After application, water and / or alcohol contained in the antifogging agent is removed and dried to form an antifogging agent layer. Since the lithium silicate and the silane derivative act as a binder for the inorganic hydrophilic colloid, the antifogging layer hardly falls off or peels off, and can maintain the antifogging effect for a long time . Use of the agricultural covering film The agricultural covering film of the present invention is used , for example, for a greenhouse such as a tunnel house or a greenhouse for cultivating crops. Here, the agricultural covering film is used so that the antifogging agent layer becomes the inner peripheral surface of the green house.

The agricultural covering film of the present invention used for the green house has a wetting tension of 30 dy on the film surface.
Since it is made of a fluororesin of ne / cm or more, the durability is good. Further, water condensed on the film surface does not become water droplets due to the action of the anti-fogging agent, but forms a continuous water film, so that water droplets hardly adhere to the inner peripheral surface of the film. Therefore, in the green house, the sunlight can hardly be blocked by the water droplets or the water droplets hardly fall on the growing plants, so that the plants can be cultivated in a favorable environment. Further, since the anti-fogging property of the film can be maintained for a long period of time, there is little need to re-apply the anti-fogging agent during the life of the film.

[0039]

EXAMPLES Examples 1 to 4, Comparative Examples 1 and 2 Examples 1 and 2 Colloidal silica (isopropyl alcohol-dispersed OSC manufactured by Catalyst Chemical Industry Co., Ltd.) was used as an inorganic hydrophilic colloid material.
AL) and (a), as a silane derivative, beta-(3,4-
Epoxycyclohexyl) ethyltrimethoxysilane and (b), as the surfactant, polyoxyethylene (1
0 mol) -lauryl ether (c) with a solid component ratio a :
The mixture was stirred and mixed so that b: c = 85: 4: 11 . The obtained mixture was dispersed in ethanol to prepare an antifogging agent having an active ingredient concentration of 20% by weight.

Fluororesin film used for coating film
As tetrafluoroethylene-hexafluoropro
Pyrene copolymer pellet "Teflon" FEP 100J
(Mitsui DuPont Fluorochemicals Co., Ltd.) supplied to the extruder
Supplied, melted by a conventional method, introduced into a T-die
A 100 μm film (A) was formed. Of the film
Roller with a processing strength of 500 W · min / m ² in air on the surface
Na discharge treatment was performed. The antifogging agent described above in the discharge treated surface, so that the solid content after drying of 0.5 g / m ² low
It was applied with a coater, and the ethanol in the antifogging agent was evaporated by hot air drying to obtain an agricultural coating film (Example
1) .

For surface treatment, do not mix oxygen in air at normal pressure.
Plasma treatment with treatment intensity of 700 W · min / m ²
Agricultural coatings were carried out in exactly the same manner as in Example 1 except that
A film was obtained (Example 2). Examples 3 and 4 As the fluororesin film used for the coating film,
Lafluoroethylene (53 mol)-ethylene (46
) -Perfluorobutylethylene (1 mol) copolymer
The pellets were filled with a 100 μm thick
(B) was formed. Treating the film surface in air
Than was subjected to corona discharge treatment at an intensity 60W · min / m ²
Outside, an agricultural covering film was obtained in the same manner as in Example 1.
(Example 3).

For surface treatment, do not mix oxygen in air at normal pressure.
Plasma treatment at a processing intensity of 300 W · min / m ²
Agricultural coatings were carried out in exactly the same manner as in Example 1 except that
A film was obtained (Example 4). Comparative Examples 1 and 2 The surface of the fluororesin film (A) used in Examples 1 and 2
Same as Example 1 except that an antifogging agent was applied without treatment
To obtain an agricultural covering film (Comparative Example 1).

Fluororesin film used in Examples 3 and 4
No surface treatment of (B) was carried out except that an antifogging agent was applied.
An agricultural covering film was obtained in the same manner as in Example 1 (Comparative Example).
2).

[0044]

[Table 1] Examples 5 and 6, Comparative Example 3 The same agricultural coating film as in Example 1 was produced by changing the corona discharge treatment conditions of the fluororesin film (A) used in Example 1 as shown in Table 2.

[0045]

[Table 2] Example 7, Comparative Examples 4 to 6 Methanol silica sol (manufactured by Nissan Chemical Industries, Ltd.) (a)
β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (b) and polyoxyethylene (8 mol)
Nonyl phenyl ether (c) and a solid content ratio of a: b:
The mixture was stirred and mixed so that c = 80: 7: 13. Then, the obtained mixture was dispersed in ethanol to prepare an antifogging agent having an active ingredient concentration of 20% by weight.

The anti-fogging agent was dried at a solid content of 0.4%.
g / m ² was applied to the films shown in Table 3 using a roll coater. Then, the ethanol in the antifogging agent was evaporated by hot-air drying to obtain an agricultural coating film.

[0047]

[Table 3] Examples 8, 9 Methanol silica sol (manufactured by Nissan Chemical Industries, Ltd.) (a)
γ-glycidoxypropyltriethoxysilane (b)
And polyoxyethylene (10 mol) -nonylphenyl ether (c) having a solid part ratio of a: b: c = 90: 1:
The mixture was stirred and mixed to 9 Then, the obtained mixture was dispersed in ethanol to prepare an antifogging agent having an active ingredient concentration of 20% by weight. This antifogging agent was applied to the same film as used in Examples 3 and 4, to obtain an agricultural coating film. The combination of the film used in Example 3 and the antifogging agent is Example 8, and the combination of the film used in Example 4 and the antifogging agent is Example 9. Example 10 Takedak A manufactured by Takeda Pharmaceutical Co., Ltd., which is a polyurethane composition, was applied to the surface-treated surface of the film used in Example 2.
Blends of -310 and Takenate A-3 (12: 1) was coated so as to be 0.2 g / m ² in a solid content. This mixture was heated to polymerize while removing the solvent and forming an underlayer.

The antifogging agent used in Example 2 was applied on the underlayer so that the solid content after drying was 0.5 g / m ^2, and dried to form an antifogging agent layer. Thereby, an agricultural covering film was obtained. Example 11 The surface of the film used in Example 3 was treated with Example 10
An underlayer was formed in the same manner as described above. And on this underlayer,
The antifogging agent used in Example 3 was applied under the same conditions as in Example 10 to form an antifogging agent layer. Thereby, an agricultural covering film was obtained. Evaluation (1) About the agricultural coating films obtained in Examples 1 to 9 and Comparative Examples 1 to 6, antifogging property and antistatic property were evaluated. Table 4 shows the results. The evaluation method is as follows. Antifogging Add 100 ml of water to a 200 ml beaker. The beaker was covered with an agricultural covering film so that the antifogging agent layer was on the inside, and the film was stopped with a rubber band.

The beaker covered with the film was immersed in a constant temperature water bath and heated under the following heating conditions. Then, the state of attachment of water droplets to the film during that time was observed. (Heating conditions) 3
0 ℃ × 5days → 50 ℃ × 10days → 60 ℃ × 10days → 70 ℃
× 30 days. These heating conditions correspond to about three years of practical use in a green house.

The evaluation criteria are as follows. ：: no clouding due to water droplets. Δ: Water droplets adhered to a part.

×: Water droplets adhered to the entire surface. Antistatic Property The surface resistivity was measured in an atmosphere of 20 ° C. and 60% RH. For measurement, use Universal Electrometer Mo
del MMAII-17 (manufactured by Kawaguchi Electric Works, Ltd.) and a P-601 type measurement box (manufactured by the company) were used.

The relationship with the anti-fog performance is as follows. 10 ¹¹ or less: no clouding due to water droplets
No. 10 ¹² to 10 ¹³ : Water droplets adhere to a part.

10 ¹⁴ or more: Water drops on the front surface from more than half
To wear.

[0054]

[Table 4] (2) The antifogging properties of the agricultural covering films obtained in Examples 10 and 11 were evaluated by the same method as in the above (1). However, the heating condition at 70 ° was changed to 70 ° × 50 days. Table 5 shows the results. Table 5 also shows the antifogging properties of Examples 2 and 3 for comparison.

[0055]

[Table 5] As is clear from Table 5, when the underlayer is provided, the anti-fogging effect is maintained for a longer time.

[0056]

According to the first aspect of the present invention, since the above-described antifogging agent layer is disposed on the fluororesin film layer having specific surface characteristics , the durability and the antifogging property are improved. An agricultural covering film that can be favorably maintained for a long time can be realized.

In the second invention, since the underlayer is formed between the fluororesin film layer having specific surface characteristics and the above-described antifogging agent layer, the durability is good. It is possible to realize an agricultural covering film which has a good antifogging property for a long period of time.

According to the third aspect, the antifogging agent is applied after the surface treatment surface is provided on the fluororesin film, so that the durability is good and the antifogging property is well maintained for a long time. A possible agricultural covering film can be efficiently produced.

Claims (3)

(57) [Claims] 1. The film surface has a wetting tension of 30 dyne /
for agricultural use, comprising: a fluororesin film layer having a thickness of at least 10 cm ; and an antifogging agent layer comprising an inorganic hydrophilic colloid substance, a surfactant, and lithium silicate and / or a silane derivative disposed on the fluororesin film layer. Coating film. 2. A film surface having a wetting tension of 30 dyne.
/ Cm or more of a fluororesin film layer, and oxygen and / or
Or an underlayer made of an organic compound having an atomic group containing nitrogen, and an antifogging agent layer formed on the underlayer and containing an inorganic hydrophilic colloid substance, a surfactant, and lithium silicate and / or a silane derivative. An agricultural covering film comprising: 3. A step of preparing a fluororesin film, a step of providing a surface treatment surface on the fluororesin film, and an inorganic hydrophilic colloid substance, a surfactant, a lithium silicate and / or a silane derivative on the surface treatment surface. A step of applying an anti-fogging agent comprising: and a method of producing an agricultural coated film comprising: