Coating agent composition for polymer film, modified film using the same, and method for producing coating agent composition for polymer film

Abstract

To provide: a coating agent composition for a polymer film, which can form on the polymer film a film part having excellent transparency and drip-proof properties; a modified film using the same; and a method for producing the coating agent composition for a polymer film.SOLUTION: Provided is a coating agent composition for a polymer film, comprising inorganic particles and a surfactant, wherein the inorganic particles include the following alumina particles (A) and alumina particles (B). Alumina particles (A): alumina particles having a primary particle diameter of 5 nm or more and less than 11 nm. Alumina particles (B): alumina particles having a primary particle diameter of 14 nm or more and 40 nm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a coating composition for polymer films, a modified film using the same, and a method for producing a coating composition for polymer films. [Background technology]

[0002] Conventionally, transparent polymer films made of resins such as polyethylene have been widely used as films for agricultural greenhouses. However, since the surface of a polymer film is generally hydrophobic, when the film is used in an agricultural greenhouse, fine water droplets adhere to the surface due to changes in temperature and humidity, and condensation and cloudiness are likely to occur. As a result, the transmittance of sunlight decreases, which may lead to poor growth of crops. Furthermore, water droplets attached to the film may fall onto plants in the agricultural greenhouse, causing plant diseases and the like. In addition, when a polymer film is used in an agricultural greenhouse, air circulation is poor inside the greenhouse, and there is evapotranspiration from crops and water evaporation from the soil surface, so the humidity environment is likely to be higher than that outdoors. In such a high humidity environment, the composition applied to the film is likely to be washed away together with the water droplets as the period of use passes. Therefore, in addition to transparency, films used in agricultural greenhouses are required to maintain excellent drip-flow properties for a long period of time.

[0003] In order to improve the transparency and drip-proofness of a polymer film, a composition that imparts transparency and drip-proofness is widely applied to the polymer film substrate. For example, Patent Document 1 discloses an antifogging agent composition that contains three components: (A) two kinds of inorganic colloid sols with different average particle sizes that show two peaks when expressed as a particle size frequency curve and have a ratio of the average particle sizes in the range of 40 to 2, (B) a surfactant, and (C) a liquid dispersion medium. However, the transparency in a high humidity environment is not considered for the antifogging agent composition of Patent Document 1.

[0004] Patent Document 2 describes a method for producing a polyether-modified silicone having 10 to 50 parts by mass, and a starting compound having at least one selected from an aliphatic alcohol having 8 to 22 carbon atoms, a fatty acid having 8 to 22 carbon atoms, an alkylphenol having 8 to 22 carbon atoms in the alkyl group, and a monoalkylamine having 8 to 22 carbon atoms, wherein ethylene oxide is added at a rate of 3 to 100 moles per mole of starting compound, the starting compound being at least one selected from an aliphatic alcohol having 8 to 22 carbon atoms, a fatty acid having 8 to 22 carbon atoms, an alkylphenol having 8 to 22 carbon atoms in the alkyl group, and a monoalkylamine having 8 to 22 carbon atoms, to 100 parts by mass of an inorganic cationic colloidal sol having 20 to 100 mass% of cationic alumina sol and 0 to 80 mass% of cationic silica sol in solid content (total 100 mass% in solid content). A thermoplastic polymer film coating composition is disclosed, which is characterized by comprising 2 to 30 parts by mass of a polyoxyalkylene derivative consisting of at least one selected from a compound in which ethylene oxide and propylene oxide are randomly added in a total ratio of 3 to 100 moles per mole of the starting compound, a compound in which ethylene oxide and propylene oxide are added in a block form in a total ratio of 3 to 100 moles per mole of the starting compound, and 45 to 75 parts by mass of an ethylene oxide-propylene oxide block polymer having a number average molecular weight of 1000 to 9800. However, in the thermoplastic polymer film coating composition of Patent Document 2, the evaluation of dripping property is performed after 1 day and 30 days, and there is no consideration as to whether dripping property is maintained for a long period of time such as about one year. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 60-69181 [Patent Document 2] JP2018-127546A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present disclosure is to provide a coating composition for polymer films capable of forming a coating portion having excellent transparency and drip resistance on a polymer film, a modified film using the same, and a method for producing the coating composition for polymer films. [Means for solving the problem]

[0007] The present invention takes the following measures to solve the above problems. [1] A coating composition for a polymer film, comprising inorganic particles and a surfactant, wherein the inorganic particles comprise the following alumina particles (A) and the following alumina particles (B). Alumina particles (A): Alumina particles with a primary particle diameter of 5 nm or more and less than 11 nm Alumina particles (B): Alumina particles with a primary particle diameter of 14 nm or more and 40 nm or less. [2] The coating agent composition for polymer films according to [1], comprising 20 to 90 parts by mass of the alumina particles (A) and 10 to 80 parts by mass of the alumina particles (B), relative to 100 parts by mass of the total content of the alumina particles (A) and the alumina particles (B). [3] The coating composition for polymer films according to [1], wherein the sum of the content of the alumina particles (A) and the content of the alumina particles (B) is 60 mass% or more when the content of the inorganic particles is 100 mass%. [4] The coating composition for polymer films according to [1], wherein the inorganic particles have an oil absorption of 70 ml / 100 g or more. [5] The coating composition for polymer films according to [1], wherein the surfactant is a nonionic surfactant. [6] A modified film comprising a base film portion made of a synthetic resin film and a coating portion comprising any one of the polymer film coating compositions [1] to [5] on at least a portion of the surface of the base film portion. [7] A method for producing a coating composition for a polymer film according to any one of [1] to [5], The method includes a step of mixing the inorganic particles including the alumina particles (A) and the alumina particles (B) with the surfactant, The method for producing alumina, characterized in that the alumina particles (A) and the alumina particles (B) are supplied from separate sources.

[0008] In this specification, the numerical range indicated by "XX to △△" indicates a range including the upper and lower limits. In other words, "XX to △△" means "equal to or greater than XX and equal to or less than △△." Effect of the Invention

[0009] According to the present invention, it is possible to provide a coating composition for polymer films capable of forming a coating portion having excellent transparency and drip resistance on a polymer film, a modified film using the same, and a method for producing the coating composition for polymer films. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Coating composition for polymer film> The coating composition for polymer films of the present invention (hereinafter also referred to as "coating composition") contains inorganic particles and a surfactant, which will be described later. The inorganic particles include alumina particles (A) and alumina particles (B) described below. The inorganic particles may contain inorganic particles other than alumina particles (A) and alumina particles (B) within a range that does not impair the effects of the present invention. This allows the coating composition to impart excellent transparency and dripping properties (initial dripping properties, mid-term dripping properties, and long-term dripping properties) to the polymer film. Alumina particles (A): Alumina particles with a primary particle diameter of 5 nm or more and less than 11 nm Alumina particles (B): Alumina particles with a primary particle diameter of 14 nm or more and 40 nm or less.

[0011] <Inorganic particles> The inorganic particles may be any particles that can be dispersed in the coating composition, and conventionally known particles may be used. Examples of inorganic particles include silica (silicon oxide) particles, alumina (aluminum oxide) particles, zirconia particles, ceria particles, titanium dioxide particles, calcium carbonate particles, kaolin particles, crystalline glass filler, kaolin particles, talc particles, silica-alumina composite oxide particles, and barium sulfate particles. The shape of the inorganic particles is not particularly limited, and may be spherical, irregular, needle-like, plate-like, or the like. One or more types of inorganic particles may be used.

[0012] <Alumina particles> The alumina particles are not particularly limited, and can be appropriately selected from conventionally known alumina particles. Examples of alumina constituting the alumina particles include alumina hydrate, α-alumina, γ-alumina, θ-alumina, δ-alumina, and the like. The alumina particles may be natural or synthetic. In addition, the alumina particles may be appropriately selected from commercially available products, or may be prepared as desired alumina particles by heat treatment, crushing, or the like.

[0013] <Alumina particles (A)> The alumina particles (A) contained in the inorganic particles are alumina particles having a primary particle diameter of 5 nm or more and less than 11 nm. The purpose of including alumina particles (A) having a small primary particle diameter in the coating composition is to impart transparency. Alumina particles having a small primary particle diameter are less likely to scatter light. Therefore, by using a coating composition containing alumina particles (A), the transmittance increases and the transparency of the film increases. The particle diameter distribution of the inorganic particles in the present invention is determined by measuring the particle diameters of 20 inorganic particles using an electron microscope photograph.

[0014] <Alumina particles (B)> The alumina particles (B) contained in the inorganic particles are alumina particles having a primary particle diameter of 14 nm or more and 40 nm or less. The purpose of including alumina particles (B) with a large primary particle diameter in the coating composition is to improve the dripping property. By using alumina particles (B) with a large primary particle diameter, the pore volume becomes large. Therefore, the surfactant described later can be inserted more between the alumina particles (B). That is, by using alumina particles (B) with a large primary particle diameter, the oil absorption amount becomes high. Therefore, even if the surfactant flows out little by little together with the water droplets as the use period progresses, the inorganic particles containing alumina particles (B) can retain the surfactant for a long period of time. Therefore, by using a coating composition containing alumina particles (B), the dripping property can be maintained for a long period of time.

[0015] <Oil absorption of inorganic particles> The oil absorption in the present invention is the amount of surfactant absorbed by inorganic particles measured in accordance with JIS K 5101-13-1: 2004. From the viewpoint of imparting excellent long-term dripping properties, the oil absorption of the inorganic particles is preferably 70 ml / 100 g or more, and more preferably 80 ml / 100 g or more.

[0016] <Composition ratio of coating agent composition> The mixing ratio of the alumina particles (A) and the alumina particles (B) in the coating agent composition is not particularly limited, but when the total content ratio of the alumina particles (A) and the alumina particles (B) is 100 parts by mass, the alumina particles (A) are preferably contained in an amount of 20 to 90 parts by mass and the alumina particles (B) are preferably contained in an amount of 10 to 80 parts by mass.More preferably, the alumina particles (A) are preferably contained in an amount of 40 to 90 parts by mass and the alumina particles (B) are preferably contained in an amount of 10 to 60 parts by mass.

[0017] As described above, from the viewpoint of transparency, alumina particles having a small primary particle size are less likely to scatter light, and thus, by including them in the coating composition, the transparency of the film coated with the coating composition is increased. On the other hand, alumina particles having a large primary particle size are more likely to scatter light, and thus, by including them in the coating composition, the film coated with the coating composition becomes whitish. From the viewpoint of long-term dripping property, the higher the oil absorption of the inorganic particles, the longer the surfactant can be retained, and the better the long-term dripping property becomes, but alumina particles having a small primary particle size have a small pore volume and therefore a low oil absorption. On the other hand, alumina particles having a large primary particle size have a large pore volume and therefore a high oil absorption. Therefore, in order to achieve both excellent transparency and long-term dripping property, it is preferable to use the above-mentioned blending ratio of the coating composition.

[0018] Moreover, alumina particles having a primary particle diameter between the primary particle diameter of the alumina particles (A) and the primary particle diameter of the alumina particles (B) are referred to as alumina particles (C) below. Alumina particles (C): Alumina particles with a primary particle diameter of 11 nm or more and less than 14 nm When the total content of the alumina particles (A), the alumina particles (B), and the alumina particles (C) is taken as 100 parts by mass, the content of the alumina particles (C) is preferably 0 to 10 parts by mass. This is because the lower the content of the alumina particles (C), the easier it is to obtain the effects of the two types of alumina particles (A) and (B) having different particle sizes.

[0019] <Surfactant> The surfactant is not particularly limited, and conventionally known surfactants can be used. Examples include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are preferred from the viewpoint of dispersibility of inorganic particles. These surfactants may be used alone or in combination of two or more. The surfactant is preferably used in an amount of 5 to 200 parts by mass, more preferably 5 to 100 parts by mass, per 100 parts by mass of inorganic particles.

[0020] <Nonionic surfactant> The nonionic surfactant is not particularly limited, and may be appropriately selected from conventionally known nonionic surfactants, such as polyether-modified silicone, polyoxyethylene stearyl ether, polyoxyethylene stearate, polyoxyethylene nonylphenol ether, polyoxyethylene polyoxypropylene oleate, and polyoxyethylene polyoxypropylene lauryl ether.Others include (1) compounds in which an alkylene oxide having 2 to 4 carbon atoms is added to an organic acid, an organic alcohol, an organic amine, and / or an organic amide, such as polyoxyethylene dilaurate, polyoxyethylene oleate, polyoxyethylene dioleate, polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene lauryl ether methyl ether, polyoxypropylene lauryl ether methyl ether, polyoxyethylene oleyl ether, polyoxyethylene polyoxypropylene nonyl ether, polyoxyethylene polyoxypropylene octyl ether, an ethylene oxide adduct of 2-hexylhexanol, polyoxyethylene 2-ethyl-1-hexyl ether, polyoxyethylene isononyl ether, polyoxyethylene dodecyl ether, a compound in which ethylene oxide is added to secondary dodecyl alcohol, and polyoxyethylene tridecyl (2) polyoxyalkylene polyhydric alcohol fatty acid ester type nonionic surfactants such as polyoxyalkylene sorbitan trioleate, polyoxyalkylene coconut oil, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene hydrogenated castor oil trioctanoate, polyoxyalkylene hydrogenated castor oil maleate, stearic acid ester, or oleic acid ester; (3) alkyl amide type nonionic surfactants such as stearic acid diethanolamide and diethanolamine monolauroamide; and (4) polyoxyalkylene fatty acid amide type nonionic surfactants such as polyoxyethylene diethanolamine monooleylamide, polyoxyethylene laurylamine, and polyoxyethylene beef tallow amine. These nonionic surfactants may be used alone or in appropriate combination of two or more. Among these nonionic surfactants, polyethers are more preferred.

[0021] <Anionic surfactant> The anionic surfactant is not particularly limited, and any of the conventionally known anionic surfactants can be appropriately selected and used. For example, (1) phosphoric acid ester salts of aliphatic alcohols such as lauryl phosphate salts, cetyl phosphate salts, octyl phosphate salts, oleyl phosphate salts, and stearyl phosphate salts; (2) phosphoric acid ester salts of aliphatic alcohols to which at least one alkylene oxide selected from ethylene oxide and propylene oxide has been added, such as polyoxyethylene lauryl ether phosphate salts, polyoxyethylene oleyl ether phosphate salts, and polyoxyethylene stearyl ether phosphate salts; (3) aliphatic sulfonates or aromatic sulfonates, such as lauryl sulfonate, myristyl sulfonate, cetyl sulfonate, oleyl sulfonate, stearyl sulfonate, tetradecane sulfonate, dodecyl benzene sulfonate, and secondary alkyl sulfonate (C13-15) salts; (4) sulfate ester salts of aliphatic alcohols such as lauryl sulfate salts, oleyl sulfate salts, and stearyl sulfate salts; (5) polyoxyethylene lauryl ether sulfate salts, polyoxyalkylene (poly ... (5) sulfates of fatty alcohols to which at least one alkylene oxide selected from ethylene oxide and propylene oxide has been added, such as polyoxyethylene, polyoxypropylene) lauryl ether sulfate and polyoxyethylene oleyl ether sulfate; (6) castor oil fatty acid sulfate, sesame oil fatty acid sulfate, tall oil fatty acid sulfate, soybean oil fatty acid sulfate, rapeseed oil fatty acid sulfate, palm oil fatty acid sulfate, lard fatty acid sulfate, and beef tallow; (7) sulfate salts of fats and oils, such as sulfate salts of castor oil, sulfate salts of sesame oil, sulfate salts of tall oil, sulfate salts of soybean oil, sulfate salts of rapeseed oil, sulfate salts of palm oil, sulfate salts of lard, sulfate salts of beef tallow, and sulfate salts of whale oil; (8) fatty acid salts, such as laurates, oleates, and stearates; and (9) sulfosuccinate salts of fatty alcohols, such as dioctyl sulfosuccinate.These anionic surfactants may be used alone or in appropriate combination of two or more kinds.

[0022] <Cationic surfactant> The cationic surfactant is not particularly limited, and conventionally known cationic surfactants can be appropriately selected and used. For example, lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, didecyl dimethyl ammonium chloride, 1,2-dimethyl imidazole, triethanolamine, etc. can be mentioned. These cationic surfactants can be used alone or in combination of two or more.

[0023] <Amphoteric surfactant> The amphoteric surfactant is not particularly limited, and may be appropriately selected from conventionally known amphoteric surfactants, such as betaine-type amphoteric surfactants.

[0024] <Other additives> Other conventionally known additives may be added to the coating composition depending on the purpose, such as binders, colorants, antioxidants, light stabilizers, flame retardants, antistatic agents, antifungal agents, antibacterial agents, antifouling agents, ultraviolet absorbers, preservatives, lubricants, etc.

[0025] <Modified film> The modified film of the present invention comprises a base film part made of a synthetic resin film and a coating part containing a coating composition on at least a part of the surface of the base film part. The coating part of the modified film may be formed on only one side of the base film part or on both sides.

[0026] <Base film section> The base film part is not particularly limited as long as it is made of a synthetic resin film. The base film part may be either a thermoplastic resin film or a thermosetting resin film, but in the present invention, a thermoplastic resin film is preferred. Examples of thermoplastic resins include olefin resins, polyester resins, vinyl chloride resins, vinylidene chloride resins, ethylene-vinyl acetate copolymers, ethylene-alkyl methacrylate ester copolymers, ethylene-vinyl alcohol copolymers, polyvinyl alcohol, cyclic olefin resins, acrylic resins, aromatic vinyl resins, polyamide resins, and polyurethane resins. The base film part may be a single layer or a multilayer.

[0027] Examples of the olefin resin include homopolymers of ethylene or α-olefins having 3 or more carbon atoms, ethylene-α-olefin copolymers, and copolymers of two or more α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. The olefin resin is preferably an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-vinyl acetate copolymer, a polyethylene, or an ethylene-propylene copolymer. The polyolefin resin may be used in the form of a mixture of two or more polyolefin resins.

[0028] Examples of polyester resins include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Examples of vinyl chloride resins include polyvinyl chloride, vinyl chloride-ethylene copolymer, vinyl chloride-vinyl acetate copolymer, etc.

[0029] Other conventionally known resin additives may be added to the base film portion depending on the purpose, such as antioxidants, weathering agents, ultraviolet absorbers, infrared absorbers, lubricants, antiblocking agents, antifogging agents, anti-fog agents, heat retaining agents, colorants, etc.

[0030] The base film part used in the modified film may be surface-treated by corona discharge treatment, atmospheric pressure plasma treatment, flame treatment, etc., or may have a surface on which an undercoat layer is formed. The thickness of the base film part is not particularly limited.

[0031] The method for providing a coating portion containing a coating composition on a base film portion is not particularly limited, and a conventionally known method can be used. For example, gravure coating, spray coating, dip coating, roll coating, doctor blade coating, wire bar coating, air knife coating, etc. can be used. The amount of coating composition applied to the base film portion and the thickness of the coating are not particularly limited, but the coating after drying is preferably 0.05 to 3.0 g / m 2 is preferably 0.1 to 2.0 g / m 2 is more preferred.

[0032] After applying the coating composition to the base film portion of the modified film, the formed coating film may be dried as necessary. When drying is performed, the coating film can be dried by natural drying, cold air drying, hot air drying, infrared drying, or a combination of these.

[0033] Although there is no particular limitation on the use of the modified film of the present invention, it is particularly preferable to use it in an agricultural greenhouse, because by spreading the modified film with the surface of the coating part of the modified film tilted and facing the ground, water droplets adhering to the surface of the coating part can be made to flow downward along the modified film.

[0034] <Method for producing coating composition> The method for producing the coating composition includes a step of mixing inorganic particles including alumina particles (A) and alumina particles (B) with a surfactant, and is not particularly limited as long as the alumina particles (A) and the alumina particles (B) are supplied from separate sources. For example, the coating composition is produced by mixing and stirring the alumina particles (A) in a liquid solvent to disperse the alumina particles (A) in the liquid solvent, then adding the alumina particles (B) and mixing and stirring to disperse the alumina particles (B) in the liquid solvent, and further adding and mixing a surfactant. Alternatively, the coating composition may be produced by adding a surfactant to a liquid solvent and mixing and stirring, and further adding the alumina particles (A) and the alumina particles (B) and mixing and stirring. Alternatively, the alumina particles (A), the inorganic particles (B), the surfactant, and other raw material components may be mixed together.

[0035] The polymeric film coating composition of the present invention is suitable for application to synthetic resin films, but also when a coating portion is formed on a substrate made of a metal or inorganic compound, or a composite substrate having a layer formed on the surface of the substrate, an article having a coating portion excellent in transparency and drip resistance can be formed. EXAMPLES

[0036] Below, examples and comparative examples are given that more specifically illustrate the configuration and effects of the present disclosure, but the present disclosure is not limited to these examples. In the following examples and comparative examples, "parts" and "%" are based on mass. Table 1 shows the raw material components of the coating agent composition and the oil absorption of inorganic particles used in each example and comparative example.

[0037] <Raw materials for coating composition> The raw materials used in the production of the coating composition are as follows.

[0038] <Alumina particles (A)> A-1: Plate-shaped alumina sol with a primary particle diameter of 5 nm or more and less than 11 nm A-2: Feathery alumina sol with a primary particle diameter of 5 nm to less than 11 nm

[0039] <Alumina particles (B)> B-1: Plate-shaped alumina sol with a primary particle diameter of 14 nm to 30 nm B-2: Block-shaped alumina sol with a primary particle diameter of 14 nm to 30 nm

[0040] <Other> C-1: Alumina-modified silica sol with a primary particle diameter of 10 nm to 20 nm C-2: Alumina-modified silica sol with a primary particle diameter of 40 nm to 60 nm C-3: Silica sol with primary particle diameter of 10 nm to 20 nm C-4: Silica sol with primary particle diameter of 40 nm to 60 nm C-5: Plate-shaped alumina sol with a primary particle diameter of 11 nm or more and less than 14 nm

[0041] <Surfactant> D-1: Main chain / side chain = 50 / 50 (mass ratio), ethylene oxide / propylene oxide = 100 / 0 (molar ratio), 25°C kinematic viscosity 600mm 2 / s Polyether modified silicone D-2: 20 moles of ethylene oxide adduct of stearyl alcohol D-3: 12 mole ethylene oxide adduct of stearic acid D-4: Nonylphenol ethylene oxide 10 mole adduct D-5: 9 moles of ethylene oxide and 9 moles of propylene oxide random adduct of oleic acid D-6: 9 mol ethylene oxide and 9 mol propylene oxide block adduct of lauryl alcohol

[0042] <Preparation of Coating Composition and Measurement of Oil Absorption> A coating composition was prepared using the above-mentioned raw materials. Then, the oil absorption of the inorganic particles in the obtained coating composition was measured.

[0043] <Coating composition X-1> 500 parts of alumina particles (A) (A-1: solid content 15%) and 167 parts of alumina particles (B) (B-1: solid content 15%) were added to 6790 parts of water, and the mixture was stirred and mixed for 30 minutes or more to completely disperse the particles in water. 50 parts of surfactant (D-1) were further added and the mixture was stirred and mixed for 30 minutes or more to prepare a coating composition (X-1) with a pure content of 2%.

[0044] <Coating compositions X-2 to X-11 and x-1 to x-10> Coating compositions (X-2) to (X-11) and (x-1) to (x-10) having the compositions shown in Table 1 below were prepared in the same manner as for coating composition X-1.

[0045] <Oil absorption measurement of inorganic particles> Next, each of the obtained coating compositions X-1 to X-11 and x-1 to x-10 was vacuum-dried at 40°C, and then the surfactant was extracted from the obtained dried product using chloroform to obtain inorganic particles. The inorganic particles were pulverized in a mortar, and the oil absorption per 100g of inorganic particles was measured according to a method conforming to JIS K 5101-13-1:2004. The results are shown in Table 1.

[0046] [Table 1]

[0047] <Preparation of base film> Next, a base film onto which the coating composition was applied was prepared.

[0048] <Production Example 1> Ethylene-1-butene copolymer (ethylene unit content: 95%, density: 0.920 g / cm 3The olefin polymer film was subjected to a corona discharge treatment on its surface to obtain a surface-treated olefin resin film (hereinafter referred to as "base film (F-1)"). The wet tension of the corona discharge treated surface was measured by a method conforming to JIS K 6768 and was found to be 44 mN / m.

[0049] <Production Example 2> Instead of ethylene-1-butene copolymer, ethylene-1-hexene copolymer (ethylene unit content: 96%, density: 0.930g / cm 3 A surface-treated olefin resin film (hereinafter referred to as "base film (F-2)") was obtained by the same procedure as in Preparation Example 1, except that a 1.0 g / 10 min. cellulose acetate sheet (MFR: 1.0 g / 10 min.) was used. The wet tension of the corona discharge-treated surface was 40 mN / m.

[0050] <Preparation Example 3> A surface-treated olefin resin film (hereinafter referred to as "base film (F-3)") was obtained by the same procedure as in Preparation Example 1, except that an ethylene-vinyl acetate copolymer (ethylene unit content: 93%, MFR: 1.5 g / 10 min) was used instead of the ethylene-1-butene copolymer. The wetting tension of the corona discharge-treated surface was 42 mN / m.

[0051] <Preparation Example 4> Instead of ethylene-1-butene copolymer, polyethylene (density: 0.927 g / cm 3 A surface-treated olefin resin film (hereinafter referred to as "base film (F-4)") was obtained by the same procedure as in Preparation Example 1, except that a 100% ethylenediaminetetraacetate (E10) was used. The wet tension of the corona discharge-treated surface was 44 mN / m.

[0052] <Preparation Example 5> Instead of ethylene-1-butene copolymer, ethylene-propylene copolymer (ethylene unit content: 4%, density: 0.90g / cm 3A surface-treated olefin resin film (hereinafter referred to as "base film (F-5)") was obtained by the same procedure as in Preparation Example 1, except that a 100% ethylenediaminetetraacetate (E10) was used. The wet tension of the corona discharge-treated surface was 43 mN / m.

[0053] <Production and evaluation of modified films> The modified film was prepared using the above coating composition and base film. The coating surface of the modified film was then evaluated for transparency and drip resistance by the following method.

[0054] <Example 1-1> The coating composition (X-1) was applied to the corona discharge treated surface of the base film (F-1) in an oven-dry coating amount of 0.3 g / m 2 The coating was applied by immersion so that the coating composition (X-1) was applied to the base film (F-1) and dried at 70°C in a hot air dryer to obtain a modified film (M-1) having a coating portion containing the coating composition (X-1) on the corona discharge treatment side of the base film (F-1). The modified film (M-1) was then evaluated in the following (1) and (2). The results are shown in Table 2 below.

[0055] <Examples 1-2 to 1-11 and Comparative Examples 1-1 to 1-10> In the same manner as in Example 1-1, modified films M-2 to M-11 and m-1 to m-10 were obtained using the coating agent compositions and base films shown in Table 2 below. Then, the following evaluations (1) and (2) were performed on each of the obtained modified films. The results are shown in Table 2 below.

[0056] (1) Transparency The film was conditioned for 24 hours under conditions of 20° C. and 65% relative humidity. Thereafter, the haze value was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd. under the trade name (NDH-5000)) according to a method conforming to JIS K 7136:2000. The transparency of the film was evaluated according to the following criteria. ◎: Less than 12% (very good transparency) 〇: 12% or more to less than 14% (excellent transparency) ×: 14% or more (poor transparency)

[0057] (2) Droplet property The modified film was placed on a test house with a 15 degree inclination from the horizontal. 2 The condition of water droplets was visually observed after one day (initial dripping resistance), one month (medium-term dripping resistance), and one year (long-term dripping resistance) and evaluated according to the following criteria. ◎: Water droplets adhere to less than 10% of the surface area (excellent drip resistance) 〇: Water droplet adhesion area is 10% to less than 30% (excellent drip resistance) ×: Water droplets adhere to 30% or more of the surface area (poor dripping properties)

[0058] [Table 2]

[0059] The coating agent compositions of Examples 1-1 to 1-11 contained alumina particles (A) and alumina particles (B), and therefore had excellent transparency, initial dripping property, mid-term dripping property, and long-term dripping property. On the other hand, Comparative Examples 1-1 to 1-10 contained neither alumina particles (A) nor alumina particles (B), or contained neither alumina particles (A) nor alumina particles (B), and therefore were inferior in at least one of transparency, initial dripping property, mid-term dripping property, and long-term dripping property.

Claims

1. A coating composition for a polymer film, comprising inorganic particles and a surfactant, The coating composition for polymer films, characterized in that the inorganic particles contain the following alumina particles (A) and the following alumina particles (B). Alumina particles (A): Alumina particles having a primary particle diameter of 5 nm or more and less than 11 nm Alumina particles (B): Alumina particles having a primary particle diameter of 14 nm or more and 40 nm or less.

2. 2. The coating agent composition for polymer films according to claim 1, comprising 20 to 90 parts by mass of the alumina particles (A) and 10 to 80 parts by mass of the alumina particles (B), where the total content of the alumina particles (A) and the alumina particles (B) is 100 parts by mass.

3. 2. The coating agent composition for polymer films according to claim 1, wherein a total content of the alumina particles (A) and the alumina particles (B) is 60 mass% or more when a content of the inorganic particles is 100 mass%.

4. 2. The coating composition for polymer films according to claim 1, wherein the inorganic particles have an oil absorption of 70 ml / 100 g or more.

5. 2. The coating composition for polymer films according to claim 1, wherein the surfactant is a nonionic surfactant.

6. A modified film comprising a base film portion made of a synthetic resin film and a coating portion comprising the polymer film coating composition according to any one of claims 1 to 5 on at least a part of the surface of the base film portion.

7. A method for producing the coating composition for polymer films according to any one of claims 1 to 5, comprising the steps of: The method includes a step of mixing the inorganic particles including the alumina particles (A) and the alumina particles (B) with the surfactant, The method for producing alumina, characterized in that the alumina particles (A) and the alumina particles (B) are supplied from separate sources.

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