JP2002176862A - Drip-proof film for agriculture and horticulture, method for producing the same film and drip-proof agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drip-proof film for agriculture and horticulture, having good adhesion to a film substrate, not causing deterioration and release of coating film by long-term use and capable of keeping excellent drip-proof property over a long period and a method for producing the drip-proof film. SOLUTION: This drip-proof film for agriculture and horticulture is obtained by forming a coating film composed of a resin binder and inorganic colloid on a substrate and the coating film has uniformly scattered hollows on a substrate and average diameter of openings of the hollows is 0.1-0.5 μm and total of areas of the openings is 15-50% based on total film surface area. The coating film comprises an acrylic resin as the resin binder. The inorganic colloid has grape bunch-like shape in which 5-200 primary particles are linked and contains silica having >=0.4 g/g saturated water absorption amount as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to agricultural and horticultural films such as polyethylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, etc. having a drip-proof coating, a method for producing the same, and a coating type drip-proof composition used for the same. About.

[0002]

2. Description of the Related Art Conventionally, resin films have been used as covers for houses and tunnels for cultivating crops.
By the way, when using this resin film, the water vapor inside the house or tunnel condenses on the surface and becomes water droplets, hinders the light transmission of the film, delays the growth of crops, and further drops of water attached to the film fall, There were problems such as the occurrence of diseases on crops. To prevent these problems,
It is performed to apply a drip-proof agent to the resin film,
Various drip-proofing agents have been proposed so far. For example, Japanese Patent Publication No. Sho 50-6437 discloses an acrylic hydrophilic polymer having a hydroxyl group, and Japanese Patent Publication No. 53-37075 discloses an acrylic hydrophilic polymer containing a surfactant and a hydroxyl group. A drip-proofing agent comprising a polymer is disclosed, and Japanese Patent Publication No. 45432/1988 discloses a drip-proofing agent comprising colloidal silica and a surfactant. Japanese Patent Publication No. 64-2158 discloses a coating type drip-proofing agent comprising a copolymer containing a hydroxyl group and an acid group, an inorganic sol and a surfactant.
No. 7 discloses a drip-proofing agent comprising a copolymer containing a hydroxyl group and an acid group, colloidal silica dispersed in an alcohol, a surfactant and an alcohol. Furthermore, Japanese Patent Publication No. 4-78670 discloses a drip-proof agent comprising a hydrophobic acrylic resin having a specific glass transition temperature, a colloid sol and a surfactant. However, the drip-proofing agent composed of various combinations of these acrylic resin, surfactant and silica sol has sufficient drip-proof property at the start of use, but keeps the drip-proof property for a long time. There was a problem that it was difficult to do.
In particular, with respect to relatively low-polarity polyolefin-based films such as polyethylene and ethylene-vinyl acetate copolymer, these drip-proofing agents have a problem in that they have poor adhesion and poor durability.

[0003] To improve the drip-proof property and its durability, for example, JP-A-10-25468 discloses a drip-proof agent comprising an inorganic colloid sol, an acrylic polymer emulsion and a crosslinking agent. This drip-proof agent,
In order to improve the durability, a strong film is formed by using a crosslinking agent, and the adhesion to the film is further improved. However, also for this drip-proof agent,
The drip-proof property at the start of use and its durability are not sufficient, and further improvement is required. Further, there is also a problem that the silica sol is liable to precipitate when the coating solution of the drip-proof agent is stored, and the pot life is reduced by the crosslinking agent, making it difficult to handle.

Japanese Patent Application Laid-Open No. 7-327522 discloses a coating layer containing a synthetic resin binder and chain colloidal silica.
It is stated that a rod-shaped m, 30 to 500 nm long is effective for long-term drip-proofness. However, the present inventors have studied and found that a thin film having a coating thickness of 1 μm or less has insufficient drip-proof property and insufficient durability.

On the other hand, JP-A-9-220794 discloses a film having a coating layer composed of an ultraviolet absorbing acrylic resin and beaded colloidal silica, and a particulate acrylic resin and spherical silica are linked. It shows that the drip-proof property is good when the silica is used in combination. However, UV-absorbing acrylic resins are expensive and therefore pose a serious problem in practice. Therefore, when an acrylic resin other than the ultraviolet absorbing type is combined with the above silica, the result is that the drip-proof property is poor. Further, JP-A-11-10803 discloses a drip-proofing agent comprising a photocatalyst and rosary colloidal silica.
However, an organic binder cannot be used in the drip-proofing agent described in this publication because of the organic substance decomposition promoting property by a photocatalyst. In addition, it has excellent drip-proof properties, but has poor adhesion to a polyolefin-based film, and has a problem that its durability is insufficient.

[0006]

As described above, the conventional anti-drip agents have insufficient adhesion to polyolefin films such as polyethylene and ethylene-vinyl acetate copolymer. Further, there is a problem that the coating film is deteriorated or peeled off due to a temperature change or light during use for a long period of time, and is washed away by water droplets, resulting in a lack of drip-proof durability. In addition, there is a problem that the stability of the liquid is lacking in that sol precipitates in the liquid during storage of the drip-proofing agent.

The present invention has been made to solve the above-mentioned problems in the prior art. That is, the object of the present invention is polyethylene, ethylene-vinyl acetate copolymer, good adhesion to a film substrate such as polyvinyl chloride, without deterioration or peeling of the coating film due to long-term use, excellent It is an object of the present invention to provide a drip-proof agricultural / horticultural film capable of maintaining the drip-proof property over a long period of time and a method for producing the same. Another object of the present invention is to provide a coating-type drip-proof composition having excellent storage stability, which is used for producing the above-mentioned drip-proof agricultural / horticultural film.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned drawbacks. As a result, it has been found that a coating structure having a specific geometric shape is useful for improving the drip-proof property, and that a specific resin binder is used. The present inventors have found that a specific inorganic colloid improves the adhesion to a film and forms a film having a geometric shape exhibiting excellent drip-proof property, and based on this finding, completed the present invention.

That is, the drip-proof agricultural and horticultural film of the present invention is provided with a coating comprising a resin binder and an inorganic colloid on a film substrate, and the coating is provided with dents uniformly distributed on the surface thereof. The average diameter of the openings of the recesses is 0.1 to 0.5 μm, and the total area of the openings (opening area) is 15 to 50% of the total coating surface area. The coating of the present invention contains an acrylic resin as a resin binder, and as an inorganic colloid,
5 to 200 primary particles are connected in a grape-bunched shape, and are mainly composed of silica having a saturated water absorption of 0.4 g / g (silica) or more.

The above drip-proof agricultural / horticultural film of the present invention comprises:
It contains an acrylic resin as a resin binder, has a grape-bunched shape in which 5 to 200 primary particles are connected as an inorganic colloid, and has a saturated water absorption of 0.4 g / g.
(Silica) It can be produced by using an aqueous dispersion in which silica having the above-mentioned saturated water absorption is dispersed as a drip-proof composition and applying it to a film substrate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the constituent materials of the agricultural and horticultural film of the present invention will be described.
I will tell. Polyethylene, polyp
Polyole such as propylene, ethylene-vinyl acetate copolymer
Fin film, polyvinyl chloride, polyvinyl chloride
Can be used, but other conventional vinyl films can be used.
If it is used as an agricultural and horticultural film,
Anything can be used. In addition, Phil
The base material surface enhances the adhesion to the acrylic resin.
In advance, by corona discharge treatment or plasma treatment, etc.
Modified ones are preferred, and the surface tension of the film substrate surface
Power is 3.5 × 10^-Four~ 7.0 × 10^-FourN / cm, especially
3.8 × 10 ^-Four~~ 7.0 × 10^-FourIn the range of N / cm
Preferably.

The film provided on the surface of the film substrate has dents uniformly distributed on the surface, the average diameter of the opening of the dent is 0.1 to 0.5 μm, and the area of the opening is Must be in the range of 15 to 50% of the total coating surface area.

In general, the surface of the agricultural and horticultural film has a smooth flat surface or a undulating or wavy shape of 0.1 to several μm,
The sea of clouds is observed with a scanning electron microscope (SEM) (see FIG. 2). Regardless of the type or application method of the drip-proof agent, the film surface when the surface treatment is performed with a coating type drip-proof agent is in a state similar to the untreated surface, or in a state where protrusions and irregularities are increasing. . In addition, even if the film has excellent drip-proof properties at the beginning of use, the drip-proof properties will deteriorate after long-term use. However, when this surface is observed with an SEM, many cracks are present in the coating film. It is considered that this is the cause of film peeling and, consequently, the cause of deterioration of drip-proof property. As a result of examining the relationship between the surface state of such a film and the adhesion or drip-proof property, the durability thereof, the present inventor found that by using a drip-proofing agent composition having the following configuration, Average diameter 0.1
It has been found that a dent of about 0.5 μm occupies a total opening area in the range of 15 to 50% with respect to the total coating surface area, whereby a uniformly scattered coating is obtained, which has excellent drip-proof properties. Was.

That is, according to the present invention, a coating having many dents is formed by applying an aqueous dispersion containing a resin binder and an inorganic colloid described below as a drip-proofing agent composition to a film substrate. (See FIG. 1). The coating has an average diameter of the openings of .0.
The depressions in the range of 1 to 0.5 μm are uniformly scattered so as to be in the range of 15 to 50%, preferably 17 to 45% of the total opening area (opening area ratio) with respect to the total coating surface area. Although the depth of the dent varies depending on the diameter of the dent, it is generally sufficient that the depth is at least 0.1 μm.

As used herein, the term "opening" means a small hole or a small dent on the coating surface, as is apparent from FIG. FIG. 2 shows an unpainted film surface without a coating, in which undulating irregularities of 0.5 to 1 μm are observed, but there are few small holes and dents. In the present invention,
The average diameter (D) is a dent that is observed darkly by SEM (FIG. 3 shows a state of the dent that is taken by SEM).
From the width (B) and the length (L) when viewed from directly above, the formula: D
= (B + L) / 2 indicates the value obtained by arithmetically averaging the equivalent diameters obtained by the following equation. In addition, the area of a circle (πD × D /
4) is determined, and the ratio of the total area to the total coating area is determined, which is defined as the opening area ratio. In the actual measurement, based on a square coating area of 2 μm × 2 μm,
Calculate by measuring the size of all the dents therein.

The dent having an average diameter of 0.1 μm or less is hardly observed by an electron microscope, and the diameter of a water droplet formed when actually exhibiting the drip-proof property is several tens μm or more. It is not considered very effective in preventing formation. On the other hand, when the average diameter is larger than 0.5 μm, the influence of the depth of the dent on the thickness of the coating (usually 0.1 to 5 μm) increases, and the strength of the coating decreases. When the opening area ratio is 15% or less, the drip-proof property is inferior. On the other hand, when the opening area ratio is 50% or more, there are too many dents, which lowers the transparency of the coating and further lowers the coating strength.

In the present invention, the above-mentioned coating film is composed of a resin binder and an inorganic colloid as essential components.
An acrylic resin is used as the resin binder. This resin binder has a function of increasing the adhesion between the inorganic colloid and the film substrate when applied to a film substrate such as a polyolefin film. Furthermore, this resin binder has flexibility in a thin film state of several μm or less, imparts flexibility to an inorganic colloid having a small film forming ability, and even if the film base material is bent, it is accompanied by a large change in temperature. It is effective for preventing cracking and peeling of the coating due to thermal expansion and contraction of the coating and for maintaining drip-proof property for a long time.

In the present invention, the acrylic resin is preferably an acrylic resin containing at least one functional group of a hydroxyl group and a carboxyl group and / or a basic nitrogen atom. Specifically, acrylic acid or methacrylic acid [hereinafter referred to as “(meth) acrylic acid”. Produced by emulsion polymerization or solution polymerization of a mixture comprising an alkyl ester of the formula (1) and a vinyl monomer having at least one of a hydroxyl group and a carboxyl group and / or a monomer having a basic nitrogen atom. And a partially neutralized product of an acrylic resin having a carboxyl group with an organic compound having a basic nitrogen atom.

The alkyl ester of (meth) acrylic acid constituting the acrylic resin is an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group, for example, methyl (meth) acrylate, ethyl ester , N-propyl ester, isopropyl ester, n-butyl ester, 2-ethylhexyl ester, decyl ester, methoxyethyl ester, butoxyethyl ester and the like.

Examples of the vinyl monomer having at least one of a hydroxyl group and a carboxyl group include vinyl monomers having a carboxyl group such as (meth) acrylic acid and 2-acrylamido-2-methylpropanoic acid; Hydroxyethyl acrylate, hydroxylpropyl (meth) acrylate, hydroxylbutyl (meth) acrylate,
Hydroxyl-containing vinyl monomers such as N-methylolacrylamide and N, N-dimethylolacrylamide; α, β-ethylenically unsaturated carboxylic acids such as maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid; can give.

Examples of the monomer having a basic nitrogen atom include (meth) acrylic acid N, N-dimethylaminoethyl ester, N, N-diethylaminoethyl ester,
Examples thereof include N, N-dimethylaminopropyl ester, octadecylacrylamide, and an imidasol salt of (meth) acrylic acid. Examples of the organic compound having a basic nitrogen atom that neutralizes the acrylic resin having a carboxyl group include piperazine, hexamethylenediamine, imidazole, and the like.

In the acrylic resin of the present invention, 0 to 30% by weight of a copolymerizable vinyl monomer other than those described above (hereinafter, "% by weight" with respect to the content is "%" unless the effects of the present invention are impaired. "). For example, styrene, α-methylstyrene, alkenylbenzene such as vinyltoluene, a monomer that becomes a hard resin such as acrylonitrile, butadiene,
Examples of such monomers include soft resins such as isoprene and vinyl acetate. Furthermore, a small amount of a crosslinkable monomer, for example, ethylene glycol dimethacrylate, may be used in combination in order to enhance the adhesion between the film base such as a polyolefin film and the inorganic colloid. In that case, the acrylic resin has a partially crosslinked structure.

In the present invention, the monomer component of the alkyl (meth) acrylate in the acrylic resin is at least 50 to 98%, preferably 60 to 98%.
%. On the other hand, the monomer component having at least one of a hydroxyl group and a carboxyl group is 0.5 to
It is contained in the range of 50%, preferably 1 to 30%. When the content is lower than 0.5%, the water dispersibility of the acrylic resin is inferior, and when a crosslinking agent described later is used in combination, the degree of crosslinking is insufficient and the acrylic resin is used for a film substrate such as a polyolefin film. The adhesion of the resin is poor, and the durability of the drip-proof property is deteriorated. On the other hand, if it exceeds 50%, the water solubility increases, the water resistance of the coating film decreases, and the reactivity with the cross-linking agent increases. In some cases, a uniform and smooth film surface cannot be formed. When a monomer component having a basic nitrogen atom is used, the content is in the range of 1 to 30%, preferably 2 to 25%. If it is less than 1%, the effect of improving the crosslinking reactivity between the obtained acrylic resin and the epoxy group in the crosslinking agent is small. If it exceeds 30%, the basicity of the acrylic resin becomes high, the pH of the aqueous composition becomes 9.0 or more, the reactivity of the epoxy group becomes too high, the pot life becomes short, and it is used as a liquid for practical use. Not only is it difficult to perform, but also the water resistance of the coating film is reduced.

In the present invention, the acrylic resin is used as an aqueous composition. Here, the term “aqueous” means that water is used as a dispersion medium of the resin in an amount of 60% to 100%, preferably 70% to 1%.
An aqueous solvent containing 00% is used. As the aqueous solvent other than water, a water-soluble organic solvent is preferable, and specific examples include alcohols such as methanol, ethanol, and isopropanol; acetone, ketones such as methyl ethyl ketone; tetrahydrofuran, dioxane, and ethers such as ethylene glycol monomethyl ether. can give.

Therefore, the acrylic resin produced by emulsion polymerization can be used as it is. During the production of the emulsion by emulsion polymerization, the radical polymerization catalyst and surfactant, the aqueous solvent is not particularly limited,
Usually, those known in the art are used. In the case of solution polymerization, it is necessary to use an aqueous solvent after the polymerization. Therefore, it is preferable to use the above-mentioned water-soluble solvent. As the catalyst, an ordinary radical polymerization catalyst is used.

In the present invention, the inorganic colloid, which is another essential component constituting the coating, has a grape cluster-like shape in which 5 to 200 primary particles are connected and has a saturated water absorption of 0.4 g / g (silica) or more. Is used. The inorganic colloid has a function of imparting hydrophilicity to the film surface and a function of imparting an uneven shape to the film surface. That is, it is useful for forming a state in which the hydrophilicity is high and a dent is formed at the time of forming a coating film, and the surface area is increased and water droplets are destroyed, whereby the water droplets easily flow down.

Generally, silica forms spherical or rod-shaped primary particles having a particle diameter of 10 to 50 nm. The primary particles form a chain, and are “chain-like (linearly linked rod-like silica)”, “beaded (chain of spherical silica, or branched / linked bent spheres)”, Or, "grape clusters (three-dimensionally aggregated by linking spherical silica)" are known. In the present invention, grape clusters in which spherical silica is linked and aggregated three-dimensionally are used. Specifically, at least 5 to 200 spherical colloidal silica particles (primary particles) of 5 to 100 nm,
It is preferable to use one that forms a chain of 7 to 150 pieces and has a three-dimensionally connected structure.

Note that this three-dimensional connection is called a structure, and the structure shape is also observed with an electron microscope. However, numerically, as generally used in the analysis of carbon black, The evaluation is made based on the adsorption amount of a specific liquid (dibutyl phthalate in the case of carbon black). The drip-proof property in the present invention is closely related to the hydrophilic property, and it is meaningless to evaluate by the adsorption amount of dibutyl phthalate, which is a hydrophobic substance. Evaluate that you have. That is, the silica dried at 120 ° C. for 12 hours was allowed to stand in air at a humidity of 100% and a temperature of 60 ° C., and the weight increased relative to the dry silica when water was adsorbed until the weight was no longer observed. (G) is used as an evaluation standard as a saturated water absorption amount per unit silica weight (g). According to the present invention, the saturated water absorption determined in this manner is 0.1.
4 g / g (silica) or more, preferably 0.45 g / g
(Silica) The above silica is used. 0.4 saturated water absorption
If it is less than g / g (silica), the dropping property will be poor. Although there is no particular upper limit, the actually available saturated water absorption of silica is 1 g / g (silica) or less.

Since the grape cluster-shaped colloidal silica used in the present invention has many fine voids, it forms irregularities and microscopic voids even on the coating film, and tends to contain a large amount of water and water vapor. Further, it is strongly entangled with the acrylic resin, and has an effect of preventing the silica particles from falling off the coated surface. In addition, at the stage of forming the coating, the coating has pores, has a stress relaxation function, exhibits little breakage of the coating even when bent, and has a feature that it can withstand long-term use.

When the number of primary particle chains is 5 or less, the chain of the spherical colloidal silica is poor in water absorption, less entangled with the acrylic resin, and inferior in drip-proof durability. On the other hand, if the number of the primary particles is 200 or more, the shape of the agglomerated particles becomes large, and the surface unevenness when forming a coating film becomes large, thereby lowering the transparency of the film. The length of the whole grape cluster is 50 to 1,000 nm, preferably 100
５００500 nm. The surface of the silica particles can be treated with a silane coupling agent, a titanate coupling agent, or the like to increase the stability of the coating solution and the water resistance of the coating film on the film.

As the inorganic colloid in the present invention, other hydrophilic inorganic colloid sols such as spherical colloidal silica, colloidal alumina, colloidal titanium, colloidal zirconia, colloidal stannic acid, etc. are used in combination with the above-mentioned grape cluster-like colloidal silica. You can also. Further, the inorganic colloid may be a sol in which a solvent other than water, for example, an alcohol such as methanol or ethanol is mixed.

The anti-drip agent composition of the present invention comprises an aqueous dispersion obtained by mixing the above-mentioned aqueous composition of acrylic resin and the above-mentioned inorganic colloid containing grape cluster colloidal silica. The content of the acrylic resin in the drip-proof composition is 10% in the film-forming solid contained in the drip-proof composition.
-95%, preferably 25-85%, more preferably 30-65%. Also,
Grape tufted colloidal silica contains 4%
-80%, preferably 10-70%, more preferably 20-65%. When the content of the grape cluster-shaped colloidal silica is less than 4%, the total of the opening areas in the coating does not fall within the range of 15 to 50%, the effect of hydrophilicity is small, and the drip-proof property is poor. On the other hand, if it exceeds 80%, not only the transparency of the film is reduced, but also the strength of the film is reduced, and the durability of the drip-proof property is inferior.

It is preferable that the anti-drip agent composition of the present invention contains a crosslinking agent. As the cross-linking agent, a cross-linking agent having two or more epoxy groups is preferable. This is a polyfunctional compound having reactivity with a hydroxyl group and a carboxyl group, and reacts with an acrylic resin, an inorganic colloid or a surfactant described later. In addition, it acts to improve the water resistance of the coating film and to further improve the adhesion to a film substrate such as a polyolefin film. Known crosslinking agents can be used. Specific examples include a reaction product of bisphenol A and epichlorohydrin, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, diglycidyl dimer acid, triglycidyl isocyanurate, tetraglycidyl aminodiphenylmethane, cresol novolac polyglycidyl ether, triglycidyl Reaction products of polyhydric alcohols such as methylolpropane polyglycidyl ether, sorbitol or glycerol with epichlorohydrin, for example, polyoxyethylene sorbitol polyglycidyl ether and the like, and pentaerythritol polyglycidyl ether such as epoxy having two or more epoxy groups Resin can be given. These epoxy resins are usually used alone or in combination of two or more, and may be contained in the aqueous composition of the acrylic resin. In addition, in order to improve the miscibility with the aqueous composition, it is recommended that these epoxy resins have a water-soluble or water-dispersible property, but other epoxy resins have improved dispersibility in water with an emulsifier or the like. It can be used after it is in the state. A catalyst such as a tertiary amine can be further used in combination with the drip-proof composition of the present invention. Known crosslinking agents other than epoxy compounds can be used in combination as long as the effects of the present invention are not impaired.
For example, phenol resins, amino resins, amine compounds, aziridine compounds, isocyanate compounds, silane compounds and the like can be mentioned.

In the present invention, the above-mentioned crosslinking agent may be contained in the range of 0.1 to 20% in the film-forming solid of the drip-proofing agent composition. Preferably it is in the range of 0.5 to 10%, more preferably 1 to 7%. When the content of the crosslinking agent is 0.
If it is 1% or less, the crosslinking effect is not recognized, and the effect of improving the adhesion of the coating film to the film and the drip-proof property cannot be obtained. On the other hand, if it is 20% or more, the coating film becomes too hard, resulting in poor drip-proof property.

Further, the anti-drip agent composition of the present invention includes:
It is preferable to include a hydrophilic surfactant as another additive. As specific examples, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquiolate, polyoxyethylene sorbitan monolaurate, sorbitan fatty acid esters such as sorbitan triolate, polyoxyethylene sorbitol mono Sorbitol fatty acid esters such as laurate and polyoxyethylene sorbitol tetraolate, glycerin fatty acid esters such as stearic acid monoglyceride and oleic acid monoglyceride, polyglycerin fatty acid esters such as diglycerin stearic acid and decaglycerin stearic acid, and hydroxyl groups such as sucrose fatty acid esters And epoxy compounds having the formula: The amount of the hydroxyl group is preferably such that the hydroxyl value in the surfactant is 5 to 600 mgKOH / g. If the hydroxyl value is less than 5 mgKOH / g, the reactivity with the crosslinking agent is poor, and the effect of improving the adhesion of the coating film to the film and the durability of the drip-proof property is lost. In addition, 600mgK
If it is larger than OH / g, the pot life of the liquid containing the crosslinking agent will be short.

When these surfactants are contained, they may be used in the range of 0.5 to 15%, preferably 1 to 10%, more preferably 4 to 10%, in the film-forming solid of the anti-drip agent composition. The range is 9%. When the content is 0.5% or less, there is no effect of improving the drip-proof property. On the other hand, when the content is 15% or more, the adhesion durability of the coating film is poor.

Further, the anti-drip agent composition of the present invention includes:
In order to suppress the amount of light transmission and the generation of fog in the house, known additives such as an ultraviolet absorber and an antifog can be added. As the ultraviolet absorber, conventionally known ones can be used. For example, benzophenone compounds such as 2,4-dihydroxybenzophenone and benzotriazole compounds such as 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole Compounds. Examples of the antifog include low-molecular or high-molecular fluorine compounds containing a perfluoroalkyl group or a perfluoroalkenyl group, polyether-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, and amino-modified silicone oil. And the like.

In addition, in order to disperse the drip-proof agent stably in water and facilitate application on the film surface, an antifoaming agent, a wetting agent,
Additives commonly used in the coatings industry, such as film-forming auxiliaries, plasticizers, thickeners, pigments, pigment dispersants, emulsion stabilizers, etc., can be included.

The contents of the acrylic resin, the grape cluster-shaped colloidal silica, and the optional components of the crosslinking agent and the surfactant added in the drip-proof composition used in the present invention are shown below. It is on the street. That is, in the film-forming solid of the drip-proof agent composition, the acrylic resin, the grape cluster-like colloidal silica, the crosslinking agent, and the surfactant are 10 to 95%, 4 to 80%, and 0.1, respectively.
-20% and 0.5-15%. In the preferred composition of the present invention, the content of each of the above-mentioned components is 25 to 85%, 10 to 70%, 0.5 to 10% and 1%, respectively.
-10%, more preferably a composition, the content of each of the above components is 30-65%,
20-65%, 1-7% and 4-9%.

The drip-proof agricultural / horticultural film of the present invention can be produced by applying the above-mentioned drip-proof composition on the above-mentioned film substrate. Specifically, a mixture composed of the aqueous composition of the resin binder and the aqueous composition of the inorganic colloid, and, if necessary, a surfactant and other additives is prepared in advance as a main ingredient, and the crosslinking agent (curing agent) is prepared. Agent) is mixed immediately before use to form a drip-proof agent composition, and a method of applying the same or each component is separately prepared, and mixed immediately before use to form a drip-proof agent composition. Is applied. The drip-proofing composition can be diluted with a solvent such as water or alcohol at the time of use, and adjusted to a concentration and viscosity that facilitate coating. The solid concentration of the drip-proof composition is 0.5 to 20%, preferably 1 to 15%.
Is set in the range. As a method of applying the drip-proofing agent composition to the surface of the film substrate, a general coating method such as a roll coating method, a dip coating method, a brush coating method, a spray coating method, a bar coating method, a knife coating method, and a gravure coating method is used. The method implemented at the time of can be used. The coating amount of the above drip-proof agent composition is 0.01 to 5 g / solid as a solid content after drying.
m ² , preferably in the range of 0.1 to 3 g / m ² .

After the above-mentioned drip-proof agent composition is applied to the surface of the film substrate, water is evaporated by forced or natural drying to form a film. As the forced drying method, a hot air method, a far infrared radiation heat method, or the like is employed. Drying temperature is 40-130
° C, preferably in the range of 50 to 90 ° C.

[0042]

EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the following examples do not limit the present invention, and all modifications and alterations may be made without departing from the gist of the present invention. It is included in the technical scope of the present invention.

(Preparation of Aqueous Composition of Acrylic Resin) In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a raw material inlet, isopropyl alcohol (IPA) 20 was placed.
0 g, and stirring was performed while maintaining the internal temperature at 80 ° C.
A mixture consisting of the types and amounts of the monomers and catalysts shown in
It was dropped over time. After completion of the dropwise addition, 0.5 g of 2,2'-azobisisobutyronitrile (AIBN) was further added three times every hour, and the mixture was subjected to reaction aging for a total of 3 hours to reduce residual monomers. An alkaline solution shown in Table 1 was gradually added as a neutralizing agent to the obtained copolymer solution to adjust the pH to about 7. Next, after 200 g of water was added, IPA was evaporated under reduced pressure at a temperature of 55 ° C. or lower, and finally adjusted with water to obtain an aqueous composition of a copolymer having a solid concentration of 30%.

Examples 1 to 5, Comparative Examples 1 to 5, Reference Example 1 Using the aqueous composition of the acrylic resin (resin A) obtained as described above, acrylic resin: silica: polyoxyethylene sorbitol tetra An oleate = 55: a variable amount (see Table 2): an aqueous composition having a composition ratio of 7 (all in terms of solids) and a solid concentration of 30% was prepared and used as a main ingredient. Here, the types and amounts shown in Table 2 were used as silica. Then, immediately before use, sorbitol polyglycidyl ether was added to the above main agent as a crosslinking agent, and the main agent: crosslinking agent = 100: 5.
(Solids ratio), and water was further added to obtain a preparation having a solids concentration of 8% as a drip-proof composition.

The resulting preparation was applied to a 100 μm-thick polyethylene (PE) film by a bar coating method so that the coating amount (as a solid) after drying was 0.7 g / m ^2. The film was dried with hot air at 1 ° C. for 1 minute to form a film on the film, thereby producing a drip-proof agricultural / horticultural film.
The PE film used had a haze of 15.0% before coating. In addition, SE of the coating surface in Example 1 was used.
An M photograph is shown as FIG. In addition, an SEM photograph of the surface of the untreated PE film of the raw material is shown in FIG.

[0046]

[Table 1] # 1 Alkali component is used as a 5% aqueous solution. In Table 1, the symbols have the following meanings. MM
A: methyl methacrylate, BMA: butyl methacrylate, AA: acrylic acid, 2HEMA: methacrylic acid 2-
Hydroxyethyl, DMMA: dimethylaminoethyl methacrylate, EMI: 2-ethyl-4-ethylimidazole, NH _3: (using however 13% solution) ammonia purity

[0047]

[Table 2] # 1 Snowtex is a brand name of colloidal silica manufactured by Nissan Chemical Industries, Ltd., Cabosil is CABOT COR
p. Reo Seal is a trade name of Tokuyama Co., Ltd. # 2 Acryl resin: silica: polyoxyethylene sorbitol tetraolate = 55: variable amount (described in table): 7 composition ratio (all in terms of solids) Note that the saturated water absorption in Table 2 is the value as described above. That is, the silica dried at 120 ° C. for 12 hours was allowed to stand in air at a humidity of 100% and a temperature of 60 ° C., and the weight increased relative to the dry silica when water was adsorbed until the weight was no longer observed. (G) is the saturated water absorption per unit silica weight (g).

Next, the performance of the drip-proof agent composition obtained as described above and the drip-proof agricultural / horticultural film produced using the same were evaluated by the test methods described below. The results are shown in Table 3 below.

Example 6 A drip-proof agricultural / horticultural film was prepared in the same manner as in Example 1 except that sorbitol polyglycidyl ether as a crosslinking agent was not used. Table 3 shows the results. Example 7 A drip-proof agricultural / horticultural film was produced in the same manner as in Example 1 except that the acrylic resin was changed to the resin B shown in Table 1 in Example 1, and an experiment was conducted in the same manner. Table 3 shows the results. Example 8 A drip-proof agricultural / horticultural film was produced in the same manner as in Example 1 except that the acrylic resin was changed to the resin C in Table 1 in Example 1, and an experiment was conducted in the same manner. Table 3 shows the results. Example 9 A drip-proof agricultural / horticultural film was produced in the same manner as in Example 1, except that the film was changed to an ethylene-vinyl acetate copolymer film in Example 1, and an experiment was conducted in the same manner. Table 3 shows the results.

(Main agent liquid stability test):
Judgment was made according to the following evaluation criteria from the state of formation of the precipitate when stored for 0 days. ：: Uniform liquid △: Precipitated layer formed, but easily mixed when mixed lightly ×: Precipitated layer formed at bottom, not evenly mixed even with strong mixing (Liquid applicability test): Main agent When a mixture prepared by blending the mixture and a curing agent was applied to the film with a bar coater, the state of adhesion of the mixture on the film was observed and evaluated according to the following evaluation criteria. ：: The liquid does not repel at all and is uniformly wet without unevenness. △: The liquid repels a little but the liquid is almost uniform. ×: The repellency is large and a uniform coating film is not formed.

(Adhesion test): A cellophane tape was strongly adhered to the film after application and drying on the film two days later, and the state of adhesion of the film on the film and cellophane tape was observed when the film was rapidly peeled off. And evaluated according to the following evaluation criteria. ：: There is no peeling of the coating film on the film and the gloss is hardly changed. ：: There is no peeling of the coating film on the film, the gloss slightly decreases, and the gloss on the cellophane tape side also slightly decreases. However, the adhesion of the paint is also noticeably observed on the cellophane tape (transparency retention test): Changes in the haze of the film before coating and the haze after coating and drying were expressed by the following formula in terms of production%. A value closer to 100% means better. Transparency retention = {(haze before application) / (haze after application)} × 100 The haze was measured with a digital haze meter (manufactured by Nippon Denshi Kogyo Co., Ltd.).

(Accelerated drip-proof test): The film was vertically stretched 15c.
It was fixed to an acrylic frame measuring mx 7 cm in width, placed on a constant temperature water tank placed in an environment test room with a constant temperature with the coated surface facing downward, and inclined at 10 degrees to the horizontal plane. The temperature of the test room was set to 5 ° C., the temperature of the constant temperature water tank was set to 20 ° C., and the state of water droplets on the test film surface was observed over time. The evaluation criteria are as follows. 5: The film surface is uniformly wet and there are no water droplets 4: There are several water droplets, but the thickness of the water droplets is thin 3: There are many water droplets, and the water droplets are independent and flow down 2: There are many water droplets and continuous 1: Water droplets adhere to the entire surface and do not flow (Initial drip property): In the accelerated drip-proof test, the experiment started 1
After one day, one month, three months, and six months, the test film was removed from the water bath, dried under sunlight, and the accelerated drip-proof test was continued again. At the beginning of the resumption, water droplets adhered to the film test surface, but the time until the water droplets disappeared and showed the drip-proof property before resumption was measured. The shorter the time, the better the performance.

(Average diameter) 2 μm × 2 μm from SEM photograph
The portion m is copied (FIG. 3), and the length (width (B) and length (L)) of each of the pits (holes) that appear darkish is measured. B + L) /
The equivalent diameter was determined by 2 and the arithmetic mean was obtained. (Aperture area ratio) As described above, the area of the circle (πD × D / 4) was determined from the equivalent diameter, and the ratio of the total area to the total coating area was determined.

[0054]

[Table 3] # 1 PE film substrate (FIG. 2): Since there is almost no dent on the surface, the average particle size and the opening area ratio were set to “none”.

As is clear from the results shown in Table 3, the embodiment of the present invention has excellent effects. That is, the opening properties of the coating surfaces in Examples 1 to 9 were 0.1 to 0.1 in average diameter.
5 μm, the opening area ratio is 15 to 50%, and it has excellent transparency, drip-proof property, and durability. On the other hand, coatings without dents as in Comparative Examples 1 to 3 and Reference Example 1 are inferior in drip-proof properties and durability. On the other hand, in Comparative Examples 4 and 5, where the average diameter and the opening area ratio were large, the transparency was reduced and the drip-proof durability was also poor. In addition, in the case of Examples 1 to 3 in which 5 to 200 primary particles according to the present invention are connected to each other using silica having a grape-bunched shape and a saturated water absorption of 0.4 g / g (silica) or more, only the primary particles are used. Compared with Comparative Examples 1 and 2 using silica consisting of In addition, as compared with Comparative Examples 3 and 4 using silica in which rod-shaped primary particles are connected to form secondary particles, the particles have excellent drip-proof properties and initial drip properties. In the case of Comparative Example 5 using a silica having a saturated water absorption of 0.4 g / g (silica) or more, but secondary particles that are not in the form of grape tufts connected to rod-shaped primary particles, Although the dropping property is excellent, the transparency retention of the film is greatly reduced. Further, in the case of Examples 4 and 5 in which the blending amount of silica was changed, good performance was obtained as in the case of Example 1.

[0056]

The present invention has the following functions and effects, and has extremely high industrial utility value. The drip-proofing agent composition of the present invention uses silica excellent in water absorption and forms irregularities even on a coating film and maintains a high water-absorbing ability, so that it exhibits excellent drip-proofing properties. In addition, since an acrylic resin is used as the resin binder, it has excellent adhesion to polyolefins and the like, and particularly has excellent adhesion to a film surface modified by corona discharge treatment or the like.
In addition, the resin binder containing a flexible acrylic resin, and as a colloidal inorganic, using a high-structured grape cluster colloidal silica, while improving the droplet flow without lowering the transparency ,
Drops from the coating film are less than conventional silica, and drip-proofness can be maintained for a long time. Furthermore, since the drip-proofing agent composition of the present invention uses a hydrophilic acrylic resin and colloidal silica, the precipitation of silica hardly occurs, and the storage stability of the liquid is excellent.

Therefore, by using the anti-drip agent composition of the present invention, an agricultural and horticultural film having excellent drip-proof property and its durability can be easily produced. And the produced drip-proof agricultural / horticultural film of the present invention has a geometrical shape in which the coating easily forms a water film without forming a water droplet when water vapor is condensed to form a water droplet. It has excellent drip-proof properties, and has good adhesion to film substrates such as polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl chloride. It is possible to maintain excellent drip-proof properties over a long period of time without causing the occurrence of water droplets.

[Brief description of the drawings]

FIG. 1 is a micrograph (SEM) of the coating surface of Example 1.
It is.

FIG. 2 is a micrograph (SEM) of the surface of the PE film of Reference Example 1.

FIG. 3. To determine the average diameter and the open area ratio,
It is the figure of the part copied from the micrograph.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08K 3/36 C08K 3/36 C08L 33/00 C08L 33/00 (72) Inventor Tadashi Shihara Nagata-ku, Kobe City, Hyogo Prefecture No. 1-33 Hiyoshicho Honey Chemical Co., Ltd. F-term (reference) 2B024 DB01 2B029 EB03 EC03 EC04 EC16 4F006 AA12 AB24 AB76 BA10 CA06 DA04 4F100 AA01B AA20B AH02B AH03B AK04 AK25B AK25K AK53B A002B A00B A00B ARB AT00 JL00 JL07B JL11 JM01B JM10B 4J002 BG071 CD012 DJ016 FD016 FD142 GH02 HA06

Claims (7)

[Claims] A film comprising a resin binder and an inorganic colloid is provided on a film substrate, and the film has dents uniformly scattered on its surface, and the average diameter of the openings of the dents is A drip-proof agricultural / horticultural film, which is 0.1 to 0.5 μm and the total area of the openings is 15 to 50% of the total surface area of the coating. 2. The resin binder contains an acrylic resin, and the inorganic colloid has a grape cluster-like shape in which 5 to 200 primary particles are connected, and is 0.4 g / g.
The drip-proof agricultural / horticultural film according to claim 1, comprising silica having a saturated water absorption of (silica) or more. 3. The drip-proof agricultural / horticultural film according to claim 2, wherein the acrylic resin contains at least one functional group of a hydroxyl group and a carboxyl group and / or a basic nitrogen atom. 4. The drip-proof agricultural / horticultural film according to claim 2, wherein the acrylic resin is cross-linked by a cross-linking agent having two or more epoxy groups. 5. An acrylic colloid as a resin binder, and as an inorganic colloid, a grape cluster-like shape in which 5 to 200 primary particles are connected, 0.4 g / g
The method for producing a drip-proof agricultural / horticultural film according to claim 1, wherein an aqueous dispersion obtained by dispersing silica having a saturated water absorption of (silica) or more is applied to the film substrate. 6. An acrylic colloid as a resin binder, and as an inorganic colloid, a grape cluster-like shape in which 5 to 200 primary particles are connected, 0.4 g / g
(Silica) An anti-drip agent composition comprising an aqueous dispersion in which silica having a saturated water absorption of at least the above is dispersed. 7. The drip-proofing composition according to claim 6, further comprising a crosslinking agent having two or more epoxy groups.