KR102289501B1 - Coating agent for substrate, providing a surface of the substrate with hydrophilicity, Substrate coated with the coating agent and Method of making the articles - Google Patents

Abstract

According to the present invention, it is a coating agent that has excellent adhesion to a substrate having a hydrophobic surface and is treated to condense on a film when water droplets are formed on the surface of the substrate. The lower coating agent is an emulsion containing nanoparticles of a core-shell structure, the core includes poly(methyl (meth)acrylate-co-butyl acrylate), and the shell is crosslinked to the core. It is made of a poly(allyl (meth)acrylate) homopolymer attached in a network form, and the upper coating agent is provided with a coating agent comprising a hydrophilic monomer having a double bond between carbons and a photopolymerization initiator.

Description

A coating agent for imparting hydrophilicity to a substrate surface, a substrate coated with the coating agent, and a method for manufacturing the substrate

The present invention relates to a coating agent for imparting hydrophilicity to a substrate surface, a substrate coated with the coating agent, and a method of manufacturing the substrate.

When water droplets are condensed on the inner surface of a film used in a greenhouse, etc., light transmittance is lowered, and the condensed water droplets fall on crops, thereby causing mold and diseases.

The film for the greenhouse uses a polyethylene (PE) film, but the PE film is composed of hydrocarbons and has a hydrophobic surface. Condensation of water droplets on such a hydrophobic surface occurs as drop-wise condensation, and to prevent this, it induces film-wise condensation by changing to a hydrophilic surface. When water droplets are condensed on the hydrophilic surface, they spread over the surface in a film-like form rather than a spherical shape, and the condensed water flows down the hydrophilic surface rather than vertically falling. As a result, it is possible to prevent a decrease in light transmittance and a droplet phenomenon due to condensation of water droplets on the existing hydrophobic surface.

Accordingly, a technology for inducing dropwise condensation occurring on the surface of the film to membrane condensation by changing the hydrophobicity of a film for greenhouses, for example, a polyethylene (PE) film to hydrophilicity, is being developed.

As described above, most of the prior art for changing the surface of a hydrophobic substrate, including a hydrophobic film, into a hydrophilic surface is owned by foreign companies, so there is a problem of having to pay a technology royalty to use the technique.

In addition, in the substrate having a hydrophilic surface prepared by the prior art, there was still a problem in that the hydrophilic agent coated on the substrate surface disappears when the substrate surface is in contact with water, thereby reducing the hydrophilicity. Such low durability against water accelerates the replacement cycle of the substrate, resulting in an increase in the amount of discarded substrates.

Accordingly, the present inventors came to the present invention by focusing on the need to develop a unique technology for changing the surface of a hydrophobic substrate to a hydrophilic surface, which is differentiated from the prior art.

In addition, the present inventors have reached the present invention to provide a coating agent that changes the surface of the hydrophobic substrate to a hydrophilic surface, and solves the problem that the coating agent is lost even if it comes into contact with water while the coating agent is applied to the substrate and used.

In addition, the present inventors have reached the present invention to provide a method for manufacturing the coated substrate and the coated substrate.

In order to solve the above-mentioned technical problem, according to one aspect of the present invention, in a first aspect, as a coating agent,

Consists of a lower coating agent for forming a lower layer and an upper coating agent for forming an upper layer, respectively,

The lower coating agent is an emulsion containing nanoparticles having a core-shell structure, the core includes poly(methyl (meth)acrylate-co-butyl acrylate), and the shell is in the form of a network crosslinked to the core. It consists of a polymerized poly (allyl (meth) acrylate) homopolymer,

The upper coating agent is provided with a coating agent comprising a hydrophilic monomer having a carbon-to-carbon double bond (C = C) and a photopolymerization initiator.

According to a second aspect of the present invention, there is provided a coating agent in which the poly(allyl (meth)acrylate) homopolymer in the first aspect has a weight average molecular weight of 5,000 to 10,000.

According to a third aspect of the present invention, there is provided a coating agent in which the poly(allyl (meth)acrylate) homopolymer in the first or second aspect has an unsaturation of 10 to 30%.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the photopolymerization initiator is 0.05 to 5 parts by weight based on 100 parts by weight of the hydrophilic monomer having a double bond between carbons included in the upper coating agent. A coating agent is provided, which is included in an amount by weight.

According to another aspect of the present invention, in a fifth aspect,

Board; and

a coating layer formed on at least one surface of the substrate; and

The coating layer is

A lower layer comprising nanoparticles having a core-shell structure, wherein the core includes poly(methyl (meth)acrylate-co-butyl acrylate), and the shell is a poly(methyl (meth)acrylate-co-butyl acrylate) polymerized in the form of a crosslinked network on the core. (Allyl (meth) acrylate) a lower layer consisting of a homopolymer; and

An upper layer formed on the surface of the lower layer, the upper layer comprising a polymer formed from a hydrophilic monomer having a double bond between carbons;

At least a portion of the polymer formed from the hydrophilic monomer having a double bond between carbons in the upper layer is provided with a coated substrate that forms a chemical bond with the poly(allyl (meth)acrylate) of the lower layer.

According to a sixth aspect of the present invention, in the fifth aspect, at least a portion of the polymer formed from the hydrophilic monomer having the carbon-to-carbon double bond of the upper layer is a vinyl double bond of poly(allyl (meth)acrylate) of the lower layer A coated substrate is provided that forms a chemical bond with

According to a seventh aspect of the present invention, in the fifth or sixth aspect, the substrate may be a metal substrate, a glass substrate, or a polymer substrate, and in particular, there is provided a coated substrate that is a polymer substrate such as a polymer film.

In another aspect of the present invention, according to an eighth aspect of the present invention, there is provided a method for producing a substrate coated with the coating agent according to the first aspect, comprising:

forming a lower layer by coating the lower coating agent on at least one surface of the substrate and then drying;

coating an upper coating agent on the surface of the lower layer; and

There is provided a method of manufacturing a coated substrate comprising; photopolymerizing the upper coating agent.

The substrate coated with the coating agent according to the present invention has a coating layer formed on at least one surface thereof, the coating layer comprising: a lower layer formed from a lower coating agent; and an upper layer located directly on the lower layer and formed from an upper coating agent, wherein the lower layer can be coated with excellent adhesion to the surface of the substrate, in particular, to the surface of the substrate formed of a hydrophobic material, and the upper layer is a hydrophilic compound, such as , it contains a polymer formed from a hydrophilic monomer having a double bond between carbons, thereby exhibiting hydrophilicity.

As a result, even if water droplets are formed and condensed on the surface of the substrate on which the coating layer is formed by the coating agent, it is induced to film condensation instead of dropwise condensation. Accordingly, when water droplets are formed on the surface of a substrate such as a conventional greenhouse film, the water droplets are formed in a dropwise condensation method, which does not evaporate easily, but falls on crops and causes mold and diseases to be solved.

In addition, in the coating layer of the substrate coated with the coating agent according to the present invention, at least a portion of the hydrophilic monomer in the upper layer is chemically bonded to the shell component of the nanoparticles in the lower layer, specifically poly (allyl (meth) acrylate), The upper layer has the effect of being firmly fixed to the lower layer. As a result, even if water droplets are formed on the surface of the substrate, the disappearance of the constituents included in the upper layer of the coating layer by the water droplets can be suppressed or minimized.

In addition, the method of manufacturing a substrate according to the present invention uses emulsion polymerization and photopolymerization, and the advantage of emulsion polymerization is that it can be used as it is in a synthesized state, so it is a simple method without requiring separate purification and processing. It has the advantage that it can be carried out with Subsequently, photopolymerization is a polymerization method using light, and when polymerizing monomers in a mass production process, simple light irradiation and fast time are useful for introducing the process. In addition, since photopolymerization requires only a lamp to be irradiated with light, it is easy to add to the existing process, and the cost is also low. The emulsion polymerization and photopolymerization method having the above advantages are adopted together, and it becomes a coating manufacturing process and coating technology suitable for a mass production process. In addition, in the present invention, there is an advantage in that the radical formation technique or the expensive corona technique, which is known to be difficult to be applied to mass production, is not used.

In addition, since the substrate coated with the coating agent according to the present invention has high durability against water, the use period can be extended. Therefore, as the hydrophilic component is removed from the coating agent coated to make the film hydrophilic in the conventional greenhouse, the cycle is shortened to replace the film. can be significantly reduced.

In addition, according to one aspect of the present invention, the coating of each of the lower coating agent and the upper coating agent can be performed in a short time, for example, less than 1 second, and the drying and reaction time are also short, for example, adjusted to about 15 seconds. There are possible process advantages.

1 schematically shows an aspect of a manufacturing process of a lower coating agent according to the present invention.
2 schematically shows a method of manufacturing a film coated with a coating agent according to an embodiment of the present invention.
3 is a graph showing the light transmittance of the coating film of Example 1 and the film of Comparative Example 1.
4a to 4c are images taken at the contact angle of the film of Comparative Example 1, the coating film of Comparative Example 2, and the coating film of Example 1.
Figure 5a schematically shows an experimental apparatus for non-dripping evaluation of the coating film of Example 1 and the film of Comparative Example 1, and Figure 5b is the residual degree of the letters "KITECH" on the label using the experimental apparatus. A picture taken every 30 seconds is shown.
Figure 6a shows the contact angle image after washing the coating film of Example 1 and the film of Comparative Example 3, Figure 6b is a graph showing the change in the contact angle.
Figure 7a is a graph measuring the FT-IR of the lower coating agent prepared in each of Example 1 and Comparative Example 4, Figure 7b is a TGA (thermo-gravimetric analysis) analysis results, the weight change of the lower layer nanoparticles according to temperature It is expressed in weight %.

Hereinafter, the present invention will be described in detail with reference to the drawings.

According to one aspect of the present invention, as a coating agent, it consists of a lower coating agent for forming a lower layer and an upper coating agent for forming an upper layer, respectively, and the lower coating agent is an emulsion containing nanoparticles of a core-shell structure, the core contains poly(methyl (meth)acrylate-co-butyl acrylate), and the shell is made of a poly(allyl (meth)acrylate) homopolymer polymerized in the form of a cross-linked network on the core, The upper coating agent is provided with a coating agent comprising a hydrophilic monomer having a double bond between carbons and a photopolymerization initiator.

According to another aspect of the present invention, a substrate coated with the coating agent, the substrate; A coating layer formed on at least one surface of the substrate, wherein the coating layer includes nanoparticles having a core-shell structure, wherein the core includes poly(methyl (meth)acrylate-co-butyl acrylate), The shell has a lower layer made of a poly (allyl (meth) acrylate) homopolymer polymerized in the form of a cross-linked network on the core; and an upper layer formed on the surface of the lower layer, wherein the upper layer includes a polymer formed from a hydrophilic monomer having an intercarbon double bond (C=C). There is provided a substrate coated with a coating agent in which at least a portion of a polymer formed from a hydrophilic monomer having a bond forms a chemical bond with the poly(allyl (meth)acrylate) of the lower layer.

According to another aspect of the present invention, there is provided a method for manufacturing a substrate coated with the coating agent, the method comprising: coating the lower coating agent on at least one surface of the substrate and then drying the coating agent to form a lower layer; coating an upper coating agent on the surface of the lower layer; and photopolymerizing the upper coating agent; is provided.

Hereinafter, looking at the coating agent according to the present invention in more detail, the coating agent consists of an upper coating agent and a lower coating agent, respectively.

The lower coating agent is a hydrophobic coating agent having a low glass transition temperature, and is characterized in that it exhibits excellent adhesion to the surface of the substrate. This lower coating agent is an emulsion comprising nanoparticles of a core-shell structure, wherein the core comprises poly(methyl (meth)acrylate-co-butyl acrylate) as a copolymer composed of any organic monomer, The shell consists of a poly(allyl (meth)acrylate) homopolymer attached to the core in the form of a crosslinked network. Nanoparticles having such a core-shell structure have double bonds on the surface of the nanoparticles due to the compound structure constituting the shell.

As shown in FIG. 1, the poly(methyl (meth)acrylate-co-butyl acrylate) core constituting the nanoparticles was formed of methyl (meth)acrylate and butyl acrylate in the presence of an emulsifier and a polymerization initiator. It can be formed by emulsion polymerization. In addition, referring to FIG. 1 , in addition to the core, allyl (meth)acrylate is polymerized on the core, and Poly (AMA) having a double bond between carbons is formed on the outside.

In the poly(methyl (meth)acrylate-co-butyl acrylate) copolymer, methyl (meth)acrylate may be included in an amount of 0.01 to 1.00 mole fraction. Poly(methyl (meth)acrylate has a glass transition temperature of about 114 °C, and poly(butyl acrylate) has a glass transition temperature of about -49 °C, so that by controlling the molar ratio of the two components, Glass transition temperature can be controlled.In this way, by controlling the glass transition temperature of the copolymer, the coating temperature and drying time of the coating agent containing the same can also be controlled.For example, the higher the glass transition temperature, the higher the drying temperature or When the molar fraction of methyl (meth) acrylate is included in the above range, the nanoparticles including the same have an appropriate glass transition temperature, which can have the effect of controlling the drying temperature and time to a desired level. there is.

The emulsifying agent used in the emulsion polymerization of the methyl (meth)acrylate and butyl acrylate is not particularly limited, and various emulsifiers may be used. For example, emulsions of anionic surfactants (eg sodium dodecyl sulfate (SDS), etc.), nonionic surfactants, cationic surfactants, amphoteric surfactants, polymer surfactants, reactive surfactants, etc. zero can be used. You may use combining these.

The amount of the emulsifier may be used in an amount of about 0.3 to 10 parts by weight or about 0.5 to about 5 parts by weight based on 100 parts by weight of methyl (meth)acrylate and butyl acrylate.

The polymerization initiator is not particularly limited as long as it is a material that is thermally decomposed and generates radical molecules. Non-limiting examples of the polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; water-soluble azo compounds such as 2,2'-azobis(2-amidinopropane)dihydrochloride and 4,4'-azobis(4-cyanopentanoic acid); thermal decomposition initiators such as hydrogen peroxide; Redox-based polymerization initiators such as hydrogen peroxide and ascorbic acid, t-butyl hydroperoxide and rongalite, potassium persulfate and metal salts, ammonium persulfate and sodium hydrogen sulfite may be included. Moreover, you may use 2 or more types of polymerization initiators.

The amount of the polymerization initiator used is not particularly limited, and for example, it may be used in an amount of 0.1 to 2 parts by weight or 0.2 to 1 parts by weight of the polymerization initiator based on 100 parts by weight of methyl (meth)acrylate and butyl acrylate. .

In addition, in the emulsion polymerization, a reducing agent and a chain transfer agent may be further used if necessary.

In the emulsion polymerization, the polymerization temperature is not particularly limited. The polymerization temperature may preferably be in the range of 0 to 100 °C or 40 to 95 °C. The polymerization time is not particularly limited either. The polymerization time may be usually 1 to 15 hours or 5 to 20 hours.

Poly(allyl (meth)acrylate) constituting the nanoparticle shell is 0.01 to 50 parts by weight or 5 parts by weight based on 100 parts by weight of poly(methyl (meth)acrylate-co-butyl acrylate) constituting the nanoparticle core It may be included in an amount of from 20 parts by weight. Since two double bonds exist in the poly(allyl(meth)acrylate), poly(allyl(meth)acrylate) is a polymer having a network structure crosslinked by a CC single bond rather than a linear polymer with respect to the core. has a tendency to form

More specifically, allyl (meth) to form a shell after the degree of polymerization (conversion) of the poly(methyl (meth)acrylate-co-butyl acrylate) polymer corresponding to the nanoparticle core is carried out to about 70 to 80% The core-shell nanoparticles having the above-described structure can be obtained by adding the acrylate monomer in a drop-wise manner so that the shell monomer is subsequently grown at the end of the growing core polymer.

Therefore, poly(allyl (meth)acrylate) having a chemically bonded network structure has a rigid property in physical properties, and for this reason, as the content of poly(allyl (meth)acrylate) increases, cracks occur during coating While doing so, there may be a problem in that the adhesion to the substrate is lowered. When the poly(allyl (meth)acrylate) is included in the above range, there is a problem that the adhesion between the coating layer and the substrate is lowered, and the physical properties of the lower coating agent obtained by using more than the upper limit are hardened and the adhesion is reduced. can be avoided.

As the allyl (meth)acrylate, a non-wax type having a weight average molecular weight of 5,000 to 10,000 and a degree of unsaturation of 10 to 30% in order to form a shell polymer having a crosslinked network structure on the surface of the nanoparticle core. An allyl (meth)acrylate resin may be used, and in this case, proper adhesion between the lower layer and the film may be secured.

The core-shell structure nanoparticles are preferably included in an amount of 1 to 50 parts by weight or 5 to 20 parts by weight or 10 to 15 parts by weight based on 100 parts by weight of the total lower coating agent. When the core-shell nanoparticles are included in the range of the core, the coating may be appropriately performed and a coating having a thickness having a desired level of light transmittance may be formed.

Although the pH of the lower coating agent is not particularly limited, it is usually in the range of 2 to 10 or 2 to 8. The pH of the lower coating agent can be adjusted by adding aqueous ammonia, water-soluble amines, aqueous alkali hydroxide solution, etc. to the obtained emulsion.

The viscosity of the lower coating agent is usually in the range of about 10 to 10000 mPa·s or 50 to 5000 mPa·s. The viscosity was measured using a B-type rotational viscometer under conditions of 25 °C and 20 rpm.

The coating agent of the present invention further requires an upper coating agent comprising a hydrophilic monomer having a double bond between carbons and a photopolymerization initiator in order to form a hydrophilic coating layer directly on the lower layer, and such an upper coating agent is, but not limited to, as shown in FIG. can be manufactured together.

The hydrophilic monomer having a double bond between carbons imparts hydrophilicity to the coating upper layer, and at the same time, a polymerization reaction is formed between the hydrophilic monomers having a double bond between carbons to form a strong coating layer, and also nanoparticles constituting the lower layer It is chemically bonded to poly(allyl (meth)acrylate) constituting the shell component of The group having a double bond between carbons may include a (meth)acrylate group and a vinyl group, but is not limited thereto.

Non-limiting examples of the hydrophilic monomer having a double bond between carbons include 2-(meth)acryloylethyltrimethyl ammonium chloride, (2-((meth)acryloyloxy)ethyltrimethylammoniummethylphenylsulfonate, 2- ((meth)acryloyloxy)ethyltrimethylammoniummethylsulfonate, 3-((meth)acryloyloxy)propyltrimethylammoniummethylphenylsulfonate, 3-((meth)acryloyloxy)propyltrimethylammoniummethylsulfo nate, 2-(((meth)acryloyloxy)ethyltrimethylammoniummethylsulfate, 3-((meth)acrylamide)propyltrimethylammoniummethylsulfate), etc., but is not limited thereto.

The content of the hydrophilic monomer having a double bond between carbons is not particularly limited as long as it can form sufficient polymerization in the upper layer while covering the lower layer, but is not limited to 5 to 90 parts by weight or 10 to 10 parts by weight based on 100 parts by weight of the total upper coating agent. It may be included in an amount of 70 parts by weight or 20 to 40 parts by weight.

The upper coating agent further includes a photopolymerization initiator for polymerization of the hydrophilic monomer having a double bond between carbons. Examples of the photopolymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl). ]propanone}, benzyldimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxyl -2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4 acetophenone-based compounds such as -morpholinophenyl)-butanone; benzoin compounds such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acylphosphine oxide-based compounds such as 2,4,6-trimethylbenzoin diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; Benzyl such as benzyl (dibenzoyl), methylphenylglyoxyester, oxyphenylacetic acid 2-(2-hydroxyethoxy)ethyl ester, and oxyphenylacetic acid 2-(2-oxo-2-phenylacetoxyethoxy)ethyl ester compound; Benzophenone, o-benzoylbenzoic acid methyl-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, acrylated benzophenone, 3,3' ,4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 2,4,6-trimethylbenzophenone, 4-methylbenzophenone, etc. benzophenone compounds; thioxanthone-based compounds such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone compounds such as Michler's ketone and 4,4'-diethylaminobenzophenone; 10-Butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, camphorquinone, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2 -(4-methylphenylsulfonyl)propan-1-one etc. are mentioned. These photoinitiators may be used by 1 type, and may use 2 or more types together.

The photopolymerization initiator is preferably used in an amount of 0.05 to 5 parts by weight, or 0.1 to 2 parts by weight, or 1 to 2 parts by weight, based on 100 parts by weight of the hydrophilic monomer having a double bond between carbons included in the upper coating agent. When the photopolymerization initiator is used in an amount within the above range, the polymerization time of the upper coating agent is shortened, and at the same time, advantageous effects such as polymerization being started evenly over the entire surface can be obtained.

Looking at the mechanism for introducing a chemical bond between the upper layer and the lower layer, the upper layer coating agent together with the photoinitiator compound (meth) acrylate double bond present in the hydrophilic monomer is initiated under ultraviolet light to form a radical. The radical formed in this way reacts with a vinyl (vinyl) double bond present in the poly(allyl (meth)acrylate) of the lower layer, and propagation occurs. Due to this, the surface of the lower layer has radicals, and the radicals continue to react with double bonds present in the hydrophilic monomer. As a result, the hydrophilic monomer is polymerized from the surface of the lower layer, and a hydrophilic polymer is formed in the upper layer.

More specifically, the allyl (meth)acrylate used to form the nanoparticle shell of the underlying layer has two C=C double bonds, i.e., an acrylate double bond and a vinyl double bond, and each C=C A double bond has different atoms around it, so there is a difference in reactivity. In allyl (meth)acrylate, a (meth)acrylate double bond with high reactivity participates in polymerization first, and then a vinyl double bond with relatively low reactivity participates in polymerization later. According to this difference in reactivity, the vinyl double bond in the poly(allyl (meth)acrylate) homopolymer in the shell of the core-shell nanoparticles is present in an unreacted state. This unreacted vinyl double bond provides a reaction site capable of reacting C-C chemically with (meth) acrylate in the hydrophilic monomer included in the upper coating agent. Photoinitiation then results in a C-C chemical bond between the double bond in the (meth)acrylate in the hydrophilic monomer of the upper layer and the vinyl double bond in the poly(allyl(meth)acrylate) in the nanoparticle shell of the lower layer.

In summary, through photo-polymerization, a chemical bond with the hydrophilic polymer in the upper layer is made with the vinyl double bond of poly(allyl (meth)acrylate) present in the lower layer as a starting point. In general, the hydrophilic polymer has the disadvantage of being soluble in water, but in the present invention, the hydrophilic polymer forms a chemical bond with the lower layer, so it is not washed away by water, and has high durability against water.

In addition to the hydrophilic monomer having a double bond between carbons, the upper coating agent is an organic solvent, a polymerization inhibitor, a surface modifier, an antistatic agent, an antifoaming agent, a viscosity modifier, a light-resistant stabilizer, a weathering stabilizer, a heat-resistant stabilizer, and ultraviolet rays, depending on the use and required characteristics. additives such as absorbents, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, silica beads and organic beads; Inorganic fillers, such as silicon oxide, aluminum oxide, titanium oxide, zirconia, and antimony pentoxide, etc. can be mix|blended. These other combinations may be used alone or in combination of two or more.

According to another aspect of the present invention, there is provided a method for manufacturing a substrate coated with the coating agent, the method comprising: coating the lower coating agent on at least one surface of the substrate and then drying the coating agent to form a lower layer; coating an upper coating agent on the surface of the lower layer; and photopolymerizing the upper coating agent.

The substrate of the coating substrate may be a metal substrate, a glass substrate, or a polymer substrate, in particular, a polymer substrate such as a polymer film may be used, but is not limited thereto.

When a film is used as a substrate, in a specific embodiment of the present invention, the film may include, for example, a polyester-based resin such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resins such as polypropylene, polyethylene, and polymethylpentene-1; Cellulose resins, such as cellulose acetate (diacetyl cellulose, triacetyl cellulose, etc.), cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate phthalate, and cellulose nitrate; acrylic resins such as polymethyl (meth)acrylate; vinyl chloride-based resins such as polyvinyl chloride and polyvinylidene chloride; polyvinyl alcohol; ethylene-vinyl acetate copolymer; polystyrene; polyamide; polycarbonate; polysulfone; polyethersulfone; polyether ether ketone; polyimide-based resins such as polyimide and polyetherimide; Norbornene-based resin (for example, "Zeonoa" manufactured by Nippon Zeon Corporation), modified norbornene-based resin (for example, "Aton" manufactured by JSR Corporation), cyclic olefin copolymer (for example, Mitsui Chemicals Co., Ltd. "Aper"), etc. may be formed. Moreover, you may use what laminated|stacked 2 or more types of base materials which consist of these resins.

In a specific embodiment of the present invention, the film may be a polyolefin film such as a polyethylene film having a hydrophobic surface and high light transmittance, and more specifically, a polyethylene film for a greenhouse.

The film may preferably have a thickness in a range of 20 to 500 μm or a thickness in a range of 30 to 150 μm or a thickness in a range of 40 to 130 μm. By setting the thickness of the film within the above range, the phenomenon of curling (drying) the film after the lower coating agent and the upper coating agent are coated and dried on the film can be minimized.

After coating the lower coating agent on at least one surface of the substrate to be coated, it is dried to form a lower layer.

The lower coating agent is a doctor blade, gravure-coating, roll-coating, spin-coating, dip-coating, slit on at least one surface of the substrate. - It may be coated by a method such as slit-die coating or spray coating, but is not limited thereto.

The amount of the lower coating agent to be coated may vary depending on the intended use, but in one embodiment, it may be coated to form an underlayer having a thickness of 0.1 to 100 μm or 1 to 25 μm.

Then, the substrate coated with the lower coating agent is dried in a hot air oven at 20 to 50 °C or 50 to 70 °C for 0.1 to 0.5 hours or 1 to 5 hours to obtain a completely dried lower layer.

Then, after the lower layer is completely dried, the upper coating agent is coated on the surface of the lower layer.

The coating method of the upper coating agent is, for example, a doctor blade (doctor blade), gravure-coating (gravure-coating), roll-coating (roll-coating), spin-coating (spin-coating), dip-coating (dip) -coating), slit-die coating, spray coating, and the like, but is not limited thereto.

The amount of the top coating agent to be coated may vary depending on the intended use, but in one embodiment may be coated to form an upper layer having a thickness of 0.1 to 100 μm or 1 to 25 μm.

Then, the top coating is photopolymerized.

As an apparatus for irradiating ultraviolet rays to photopolymerize the upper coating agent, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, an electrodeless lamp (fusion lamp), a chemical lamp, a black light lamp, and mercury-xenon lamps, short arc lamps, helium/cadmium lasers, argon lasers, sunlight, and LED lamps.

The ultraviolet rays may have a wavelength range of 100 nm to 280 nm or a wavelength range of 200 nm to 400 nm. In addition, the ultraviolet rays are preferably irradiated for 10 to 600 seconds or 60 to 300 seconds so that a chemical bond between the upper layer and the lower layer is properly formed.

As the coating agent according to the present invention is coated on at least one surface of the substrate as described above, the substrate; a lower layer formed on at least one surface of the substrate and including the core-shell nanoparticles; and an upper layer formed on the lower layer and comprising a polymer of a hydrophilic monomer having an intercarbon double bond, wherein at least a portion of the hydrophilic monomer having an intercarbon double bond in the upper layer is poly (allyl ( A coating film chemically bonded to meth)acrylate is provided.

As described above, in the substrate coated with the coating agent according to the present invention, at least a portion of the hydrophilic monomer having a carbon-to-carbon double bond in the upper layer is chemically bonded to the shell of the core-shell nanoparticles in the lower layer, so that the upper layer is more robust to the lower layer It can have a fixed effect. As a result, even if the surface of the substrate is in contact with water or water vapor is condensed on the surface of the substrate to form water droplets, the loss of the coating agent by the water/droplets may be suppressed or minimized.

Hereinafter, the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are provided for better understanding of the present invention, and the present invention is not limited to these examples.

Example One

A polyethylene film (Lotte Chemical, FL7100U PE resin) having a thickness of 50 to 100 μm was prepared as a substrate.

The lower coating agent was prepared as follows. First, dissolved oxygen was removed by blowing nitrogen into the water. 2 g of sodium dodecyl sulfate (SDS) as an emulsifier was dissolved in 100 ml of deoxygenated water. When sodium dodecyl sulfate was completely dissolved in water, 5 ml of each of methyl methacrylate and butyl acrylate were added thereto to obtain a mixture. The mixture was maintained at 75° C., and an aqueous solution of potassium persulfate prepared by dissolving 0.1 g of potassium persulfate (KPS) in 5 ml of water as a polymerization initiator was slowly added dropwise to the mixture to cause emulsion polymerization to form an emulsion containing core particles. was made to form. Separately, as a mixture to form a shell, a mixture was prepared in which 2 ml of allyl methacrylate, 0.4 g of sodium dodecyl sulfate and 0.05 g of potassium persulfate were added to 5 ml of deoxygenated water. After 2 hours from the start of the emulsion reaction for forming the core particles, the mixture for forming the shell was added dropwise to the emulsion containing the core particles, and the reaction was terminated when 3 hours had elapsed after the completion of the dropwise addition.

The top coating was prepared as follows. 20 g of 2-methacrylatetoethyl trimethyl ammonium chloride (75% by weight aqueous solution) and 0.8 g of 2-hydroxy-2-methylpropiophenone (Danocur 1173, Sigma-Aldrich) were added to 100 g of ethanol, and a clear solution was obtained. It was stirred and stored. It was kept out of light during storage.

A lower coating agent was coated on one surface of the polyethylene film by a doctor blade, and the resulting lower layer was coated to a thickness of 10 μm. Then, it was dried in an oven at 70° C. for 10 minutes to form a completely dried 5 μm-thick lower layer. Then, the upper coating agent was coated on the surface of the lower layer by a doctor blade, and the final obtained upper layer was coated to a thickness of 20 μm. ^{Then, an ultraviolet photopolymerizer (254 nm wavelength, 2,000 mW/cm 2} ) was installed at a distance of 1.5 cm from the surface of the film coated with the upper coating agent, and photopolymerization was performed by irradiating UV for 400 seconds. The coated surface of the film became hydrophilic due to the poly[2-(methacrylateto)ethyl trimethyl]ammonium chloride in the top layer.

Whether or not the chemical bond is checked is, if there is no chemical bond between the lower coating and the upper coating, the upper coating is easily washed off with water to reveal the surface of the polyethylene film, and the contact angle has a large value due to the hydrophobic surface of the polyethylene film. On the other hand, when a chemical bond exists, since the upper coating is not washed with water, the contact angle has a low value due to the hydrophilic surface by the upper coating, which can be confirmed from the comparison of the contact angle.

comparative example One

A polyethylene film (Lotte Chemical, FL7100U PE resin) having a thickness of 50 to 100 μm was used as Comparative Example 1.

comparative example 2

Except for coating only the lower coating agent on one surface of the polyethylene film without applying the upper coating agent, a coating film to which only the lower coating agent was applied was prepared in the same manner as in Example 1, that is, Comparative Example 2.

comparative example 3

Except that the upper coating agent was directly coated on one surface of the polyethylene film without applying the lower coating agent, a coating film to which only the upper coating agent was applied was prepared in the same manner as in Example 1, that is, Comparative Example 3.

comparative example 4

A coating film was prepared in the same manner as in Example 1, except that the lower coating agent was prepared without adding allyl methacrylate.

evaluation example 1: Evaluation of optical properties

Using a UV-Vis optical spectrometer (manufacturer: Perkin Elmer, model name: Lambda 365), the light transmittance and light scattering rate of the film of Comparative Example 1 and the coating film of Example 1 were measured. In the case of light transmittance, transmittance was measured in a wavelength range of 250 nm to 700 nm, and the results are shown in FIG. 3 . In the visible light range of 400 nm to 700 nm, the average light transmittance was measured to be 86.96% for the coating film of Example 1, and 89.54% for the film of Comparative Example 1. From the above, in the case of the coating film of Example 1, it can be confirmed that high light transmittance is maintained even after coating.

Using the same UV-Vis optical spectrometer, the light scattering rate of the coating film of Example 1 and the film of Comparative Example 1 was measured through an integrating sphere. The light scattering rate of the coating film of Example 1 was measured to be 27%, and the light scattering rate of the film of Comparative Example 1 was measured to be 26%. From the above, in the case of the coating film of Example 1, it was confirmed that the light scattering rate was maintained at a level similar to that of Comparative Example 1 even after coating.

evaluation example 2: contact angle evaluation

After each of the film of Comparative Example 1, the coating film of Comparative Example 2, and the coating film of Example 1 was cut to 2 x 5 cm, 5 uL of distilled water was dropped and measured using a KRUSS DSA 100 device. As a result of the measurement, it was confirmed to have 104.2°, 76.75° and 14.91°, respectively. In addition, the contact angle images formed on the film of Comparative Example 1, the coating film of Comparative Example 2, and the coating film of Example 1 were interposed in FIGS. 4A, 4B and 4C, respectively.

evaluation example 3: Non-dripping evaluation

In the case of the coating film of Example 1 and the film of Comparative Example 1, the experimental apparatus disclosed in FIG. 5A was prepared to evaluate the degree of water vapor in contact with the film falling down, that is, the non-dripping degree. .

Referring to Figure 5a, prepare a label printed with "KITECH" letters with water-based ink, place the label on the bottom of the cup 20 containing water at a water temperature of 70 ℃, and place the cup mouth with the coating film or It was covered with the film of Comparative Example 1.

In this evaluation, the warm water in the cup is evaporated and condensed on the surface of the coating film / film. , as it reflects or scatters the transmitted light, the shape of the letters through the film is reflected and scattered and becomes opaque. As a result, "KITECH" on the label appears blurry.

The experiment with the experimental device was started, and the residual degree of "KITECH" on the label was observed and photographed every 30 seconds. The results are shown in Fig. 5b.

According to FIG. 5B, when the film of Comparative Example 1 was used, the letters "KITECH" on the label became blurred within 60 seconds of the experiment, and from this, it could be inferred that a lot of dropwise condensation occurred in the film of Comparative Example 1. On the other hand, when the coating film of Example 1 was used, the letters printed on the label remained clear even after 180 seconds after the start of the experiment, and from this, drop condensation did not occur at all or little in the coating film of Example 1 could infer.

evaluation example 4: Durability evaluation for washing

By measuring the contact angle of the coating film of Example 1 and the coating film of Comparative Example 3, the durability against washing of the coating film was evaluated.

The contact angle was measured a total of 7 times, and after cutting the film to 2 x 5 cm, 5 uL of distilled water was dropped and measured using a KRUSS DSA 100 instrument.

Except for the first contact angle measurement, each of the coating film of Example 1 and the coating film of Comparative Example 3 was washed with running water before each contact angle measurement, and then the contact angle was measured. The contact angle image is interposed in FIG. 6A, and the graph showing the contact angle change is interposed in FIG. 6B.

The coating film of Comparative Example 3 showed high hydrophilicity due to poly(2-methacrylatetoethyl trimethyl ammonium chloride), a hydrophilic polymer contained in the upper coating agent on the surface, before washing, but the contact angle increased as the number of washings progressed, for example , a phenomenon occurred that the contact angle of 87.84° after washing once increased to 104.2° after washing 6 times. This is considered to be because the poly(2-methacrylatetoethyl trimethyl ammonium chloride) was washed away by washing, and the hydrophobicity of the coating film was increased. In contrast, in the coating film of Example 1, the contact angle was 14.32 ° after washing once and the contact angle was 14.81 ° after washing 6 times, so it could be confirmed that a significant increase in the contact angle did not occur, from this, the coating of Example 1 In the film, it can be inferred that no or little loss of poly(2-methacrylatetoethyl trimethyl ammonium chloride) occurred even after washing.

From this evaluation, it is interpreted that the hydrophilic polymer of the upper coating agent can have high durability against washing when forming a bond with the lower coating agent component.

evaluation example 5: Durability evaluation for external environment

Durability evaluation with respect to temperature, humidity, and outdoor exposure of the coating film of Example 1 was performed.

First, for durability evaluation for high-temperature and high-humidity conditions, the coating film of Example 1 is stored in a thermo-hygrostat set to 100% humidity at 70 ° C., and daily at room temperature and pressure for 2 weeks (14 days) according to the following method Contact angle, light transmittance, and light scattering rate were measured. The results are shown in Table 1 below.

1) Contact angle: A DSA 100 device manufactured by KRUSS was used, and the film was cut to 2 X 5 cm and 5 uL of distilled water was added thereto.

2) Light transmittance: Perkin Elmer's Lambda 365 device was used, and the average of transmittance measured in a wavelength range of 300 to 800 nm was calculated by cutting the film to 2 X 2 cm.

3) Light scattering rate: An integrating sphere, which is one of the accessories of Perkin Elmer's Lambda 365 device, was used, and the film was measured by cutting it to 2 X 2 cm. The obtained data was processed using a program called colorimetric master.

number of days One 2 3 4 5 6 7 Contact angle (°) 14.22 14.32 14.44 14.39 14.61 15.49 15.13 Transmittance (%) 87.32 86.99 87.17 87.00 87.03 86.53 86.78 Haze (%) 27 27 26 27 27 26 27 number of days 8 9 10 11 12 13 14 Contact angle (°) 15.01 15.28 15.32 15.56 15.88 16.01 15.92 Transmittance (%) 86.12 86.10 86.09 86.07 86.10 86.01 85.99 Haze (%) 28 28 28 28 28 29 29

Second, in order to evaluate the durability for low temperature and dry conditions, a 0% humidity environment was created by placing the coating film of Example 1 in a closed reactor at -10 ° C and performing vacuum and nitrogen gas injection at least 3 times. The contact angle, light transmittance, and light scattering rate were measured according to the method described above at room temperature and pressure every day for 2 weeks (14 days), and the results are shown in Table 2 below.

number of days One 2 3 4 5 6 7 Contact angle (°) 14.11 14.15 14.69 14.35 15.00 14.75 14.62 Transmittance (%) 86.97 86.99 86.52 86.78 86.12 86.98 86.94 Haze (%) 28 27 27 27 27 27 27 number of days 8 9 10 11 12 13 14 Contact angle (°) 14.87 15.22 14.74 14.43 14.45 15.37 15.08 Transmittance (%) 87.01 86.45 86.76 87.12 87.09 86.77 86.54 Haze (%) 27 27 27 26 27 28 27

Finally, in order to evaluate the durability against outdoor exposure, the coating film of Example 1 was left outside. For outdoor exposure, the average temperature was 9 °C and the average humidity was 55%. The contact angle, light transmittance, and light scattering rate were measured according to the method described above at room temperature and pressure every day for 2 weeks (14 days), and the results are shown in Table 3 below.

number of days One 2 3 4 5 6 7 Contact angle (°) 14.76 15.02 15.13 15.17 15.64 15.97 16.14 Transmittance (%) 86.41 86.24 86.17 86.11 86.04 85.96 85.75 Haze (%) 28 28 28 28 28 28 29 number of days 8 9 10 11 12 13 14 Contact angle (°) 16.37 16.45 16.88 17.12 17.54 18.32 18.47 Transmittance (%) 85.43 85.40 85.26 85.16 85.07 85.04 85.01 Haze (%) 29 29 29 29 30 30 30

From the above, it was confirmed that the coating film of Example 1 had excellent contact angle, light transmittance, and light scattering rate in both high temperature and high humidity conditions, low temperature and dry conditions and outdoor exposure.

evaluation example 6: Physical property evaluation

FT-IR of the lower coating agent prepared in Example 1 and Comparative Example 4 was measured, and the result graph was interposed in FIG. 7A , respectively, to confirm the difference in the lower coating agent components.

In addition, TGA analysis (Thermogravimetric Analysis) of the lower coating agent of Example 1 was performed at a temperature increase rate of 10 °C/min in a temperature range of 30 °C to 600 °C, and the results are shown in FIG. 8B .

FIG. 7b is a thermo-gravimetric analysis (TGA) analysis result, showing the change in the weight of the lower layer nanoparticles according to the temperature in weight %. Through this, it can be seen that the core polymer and the shell polymer exist, respectively, since weight loss occurs in both parts. In addition, it can be seen that the coating agent of the present invention has thermal stability at a temperature up to about 200° C. before the temperature at which the core polymer is decomposed.

In the above, although the present invention has been described by limited examples and experimental examples, the present invention is not limited thereto, and the technical idea of the present invention and the Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described below.

Claims (9)

As a coating agent,
Consists of a lower coating agent for forming a lower layer and an upper coating agent for forming an upper layer, respectively,
The lower coating agent is an emulsion including nanoparticles having a core-shell structure, the core includes poly(methyl (meth)acrylate-co-butyl acrylate), and the shell is in the form of a network crosslinked to the core. It consists of a polymerized poly (allyl (meth) acrylate) homopolymer,
The core-shell structure nanoparticles have a double bond on the surface,
The upper coating agent is a coating agent comprising a hydrophilic monomer having a double bond between carbons and a photoinitiator.
According to claim 1,
The coating agent of the poly (allyl (meth) acrylate) homopolymer having a weight average molecular weight of 5,000 to 10,000.
According to claim 1,
The coating agent, wherein the poly (allyl (meth) acrylate) homopolymer has a degree of unsaturation of 10 to 30%.
According to claim 1,
The photopolymerization initiator, the coating agent is included in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the hydrophilic monomer having a double bond between carbons included in the upper coating agent.
Board; and
a coating layer formed on at least one surface of the substrate; and
The coating layer is
A lower layer including nanoparticles having a core-shell structure, wherein the core includes poly(methyl (meth)acrylate-co-butyl acrylate), and the shell includes poly(methyl (meth)acrylate-co-butyl acrylate) polymerized in the form of a crosslinked network on the core. (Allyl (meth) acrylate) a lower layer consisting of a homopolymer; and
An upper layer formed on the surface of the lower layer, wherein the upper layer is an upper layer comprising a polymer formed from a hydrophilic monomer having a double bond between carbons;
At least a portion of the polymer formed from the hydrophilic monomer having the carbon-to-carbon double bond of the upper layer forms a chemical bond with the poly(allyl (meth)acrylate) of the lower layer.
6. The method of claim 5,
At least a portion of the polymer formed from the hydrophilic monomer having the carbon-to-carbon double bond of the upper layer forms a chemical bond with the vinyl double bond of the poly(allyl (meth)acrylate) of the lower layer.
6. The method of claim 5,
A coated substrate wherein the substrate is a metal substrate, a glass substrate, or a polymer substrate.
8. The method of claim 7,
The coated substrate is that the polymer substrate is a polyethylene film.
A method for producing a substrate coated with the coating agent according to claim 1,
forming a lower layer by coating the lower coating agent on at least one surface of the substrate and then drying;
coating an upper coating agent on the surface of the lower layer; and
A method of manufacturing a coated substrate comprising a; photopolymerizing the upper coating agent.

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