Method for photocatalyst coating on plastic

Method for photocatalyst coating on plastic

The present invention relates to a manufacturing method for coating a photocatalyst on plastic. More particularly, it relates to a method of coating a nickel oxide primer on a plastic and a method of coating a titanium oxide photocatalyst, and more particularly, a nickel oxide primer used for coating a photocatalyst on a plastic and titanium oxide containing nanoparticle titanium oxide It relates to a simple manufacturing method at a low temperature within a relatively short time using microwave irradiation as a processing method for coating a photocatalyst of a precursor.

In general, a photocatalyst is a chemical change in the chemical state of the surface when exposed to light.

It is a term that refers to a material that exhibits a catalytic function that promotes a reaction.

The photocatalytic properties of titanium dioxide, a semiconductor material, are affected by ultraviolet (UV) light, resulting in a valence band.

It originates from the movement of electrons from the valence band to the conduction band.

Materials that have been studied to have activity as a photocatalyst so far include metal oxides such as TiO, ZnO, NbO, WO, SnO, and ZrO, complex metal oxides such as SrTiO, KTaO, and NiKNO17 including a plurality of metals with these, CdS, There are metal sulfides such as ZnS and metal chalcogenites such as CdSe, GaP, CdTe, MoSe, and WSe. Among them, it is preferable to use titanium oxide in terms of excellent light efficiency and light corrosion resistance, harmlessness and low price. .

The principle of such a photocatalyst will be described with reference to FIG. 1 as follows. Titanium oxide anatase used as a photocatalyst is a semiconducting metal oxide and has a bandgap energy of 3.2 eV or more or 400 nm or less. Therefore, when photon energy corresponding to this is incident, this energy is absorbed to form electron-hole pairs, and the excited holes react with moisture by strong oxidizing power to generate OH radicals, which decompose organic materials. will do The reaction process of this photocatalyst is as follows.

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The generation energy of the OH radical is equivalent to 120 Kcal/mol, and the

CC bond, CH bond, CN bond, CO bond, OH bond and NH bond

greater than the binding energy. Thus, the photocatalyst breaks these bonds. That is, since organic matter can be easily decomposed, it is widely used for removal and sterilization of contaminants, harmful substances or germs.

However, the performance of decomposing organic matter, which is a characteristic of the photocatalyst, is not suitable for products coated with the photocatalyst.

It appears as a huge limitation in production. In other words, it oxidizes organic matter, which is the advantage of photocatalyst.

The property of decomposition becomes a disadvantage in producing a product. in other words,

The generation energy of the OH radical of the photocatalyst generated from titanium dioxide is different from the CC bond, CH bond, CN bond, CO bond, OH bond, and NH bond of organic compounds.

Since it is larger than the binding energy, when the photocatalyst is directly coated on plastic,

When the photocatalyst comes into contact with the binder, it immediately oxidizes and decomposes the plastic and the binder.

occurs, discoloration occurs, the plastic and the photocatalyst are separated, and the photocatalyst efficiency is reduced.

Korean Patent 10-2010-0075850 discloses a styrene-acrylic copolymer binder (styrene

Various polymer materials such as using an acrylic copolymer binder)

was used to fix the plastic. However, using these polymer materials as binders,

In the manufactured photocatalytic plastic, the binder is oxidized and decomposed by the coated photocatalyst after 1 to 3 years. As a result, the photocatalyst-coated plastic and binder are discolored and the transparency is lowered. In addition, the photocatalyst oxidizes the binder to generate a space, which causes the photocatalyst to separate from the binder, the photocatalyst is separated from the plastic, and the photocatalytic properties of the coated photocatalyst are deteriorated.

In the Republic of Korea Patent 10-2009-0124425, as an inorganic material as a binder for a photocatalyst,

A method for preparing a photocatalyst with methyltrimethoxysilane or methyltriethoxysilane is suggested. When the silicon-based silane is used as a binder for the photocatalyst, the performance of the photocatalyst is not properly exhibited because the silane surrounds the photocatalyst, and the silane does not have good adhesion to the plastic.

Korean Patent 10-0330955 discloses that vinyl esters and/or vinyl ethers and

Fluorinated polymers containing copolymers of fluoroolefins, or silicon-based polymers, are used as binders. In this case, the site where the fluoroolefin is in contact is

It is not decomposed by photocatalysts. However, if the photocatalyst is a vinyl ester and/or a vinyl

The site in contact with the ether is decomposed. That is, such a binder is a single polymer

It has better photocatalytic decomposition prevention than using a binder, but the photocatalyst of the binder

Decomposition is not completely solved. Also with vinyl esters and/or vinyl ethers

A fluorinated polymer containing a copolymer of fluoroolefin or a silicon-based polymer with a binder envelops the photocatalyst, so there is a problem in that the photocatalyst efficiency is reduced because there are few parts protruding to the outside.

Korean Patent 2003-0038744 mentions coating a photocatalyst after coating 80 nm SiOC with a primer by CVD deposition. The SiOC primer can protect the surface of the plastic from the photocatalyst and increase the photocatalyst efficiency.

However, before coating the photocatalyst, CVD was performed to coat the SiOC with a primer. Such processing requires expensive equipment. So the production cost is high. In addition, in the case of treating the primer by CVD, the primer is produced in an amorphous form, and a post-processing of crystallization is required. Also, due to poor adhesion to plastic, the plastic and the primer fall off when bending the photocatalyst-treated plastic.

In Japanese Patent Application Laid-Open No. 9-190514, a titanium precursor is coated on plastic.

Afterwards, the photocatalyst was calcined on the plastic through microwave irradiation. Such

Firing through microwave irradiation can calcinate photocatalysts on plastics at low temperatures.

It has advantages that can be However, these photocatalysts were directly placed on plastic

As for the coating, the photocatalyst also oxidizes the surface of the plastic for the same reason as mentioned above, causing the problem of separation of the photocatalyst and the plastic.

As mentioned above, products that need to be used at low temperatures, such as plastics.

Due to the limitations in the properties of oxidizing polymer materials, which are the advantages and disadvantages of the photocatalyst,

Due to the durability problem of photocatalyst coated on plastic, there are no commercially available products.

the current situation.

<p>There are several problems to be solved in supporting photocatalysts on plastics. </p><p>a) The photocatalyst should adhere well to the plastic.</p><p>b) The photocatalytic activity should not be reduced because the photocatalyst is not impregnated on the binder. </p><p>c) Due to photocatalytic activity, the plastic should not be degraded by decomposition reaction. </p><p>d) The firing temperature of the photocatalyst should be less than or equal to the thermal deformation temperature of the plastic.</p><p>e) The photocatalyst should be able to show the performance of the photocatalyst even in UV and visible light. </p>

<p>The present invention relates to a method for producing a photocatalyst coated on plastic. More specifically, it has a two-layer structure in which a primer coating layer of nickel oxide and a coating layer of titanium oxide to which nanoparticles of titanium oxide are added are fired by microwaves on plastic.</p>

<p>In the method for manufacturing a photocatalyst in which nickel oxide is coated on plastic with a primer according to the present invention, the following effects are obtained.</p><p> A photocatalyst coated on a plastic coated with nickel oxide having a two-layer structure according to the present invention</p><p> Electrons and holes excited by ultraviolet and visible light do not recombine with each other, but are separated. </p><p>By contributing to the chemical action, the treatment efficiency is improved by about 2 times or more compared to the conventional one. </p><p>In addition, it is possible to prevent deterioration of the plastic due to the photocatalyst. Since the binder of the photocatalyst is used as the titanium oxide sol, the photocatalyst efficiency is high because both the titanium oxide nanoparticles and the titanium oxide binder exhibit the effect of the photocatalyst. And since the binder is used as titanium oxide, it is possible to prevent the efficiency from falling by enclosing the nano titanium oxide. In addition, since the binder of nano titanium oxide is composed of a mixture of anatase and rutile type, it is effective not only in ultraviolet rays but also in some visible rays. And since the oxide precursor is sintered with microwaves, the photocatalyst can be coated without deformation of the plastic.</p>

1 is a view showing the principle of operation of a general photocatalyst 2 is a view showing the structure of a photocatalyst coated on a plastic according to the present invention; 3 is a flowchart showing a manufacturing process of a photocatalyst coated on a plastic according to the present invention; 4 is a measurement result of the decomposition reaction of the photocatalyst coated on the plastic according to the present invention. drawing showing

The manufacturing method and characteristics of the photocatalyst coated on the plastic according to the present invention are as follows.

The first step is to prepare the plastic and clean the surface of the plastic,

Coating a nickel oxide primer on the second step plastic;

The third step is sintering the nickel oxide coated on the plastic with microwaves,

The fourth step is titanium oxide containing nanoparticles of titanium oxide on the calcined nickel oxide.

coating the precursor

The fifth step consists in sintering the titanium oxide precursor layer including the coated titanium oxide nanoparticles with microwaves.

The photocatalyst structure coated on the plastic according to the present invention having the above characteristics

It will be described with reference to the accompanying drawing 2 as follows. First, the concept of the present invention is that the structure of the photocatalyst coated on plastic is titanium oxide (TiO) containing nanoparticles of titanium oxide.

It has a two-layer structure in which a nickel oxide (NiO) coating layer is formed between the coating layer and the plastic.

to improve the efficiency of the photocatalyst, prevent the photocatalyst from oxidizing the plastic,

It has the performance of a photocatalyst in visible light.

3, a photocatalyst coated on a plastic having a two-layer structure according to the present invention

The manufacturing method is described as follows.

In the first step, the plastic substrate on which the photocatalyst is to be coated is mixed with alcohol, acetone,

Wash thoroughly with deionized water, etc. At this time, the reason why the plastic should be washed is because, when there is a foreign substance on the surface of the plastic, the adhesion of the oxide coating is deteriorated, and when there is a foreign substance, there is a problem that transparency is lowered. In addition, the washing operation may be omitted for continuous operation. The plastic is PE (polyethylene), PP (polypropylene), EVA (polyethylene vinyl acetate), PET (polyethylene terephthalate), PVC (polyvinyl chloride), PC (polycarbonate), PMMA (polymethylacrylate) ), PI (polyimide), PBT (Polybutylene Terephthalate), Polyamide, polyurethane, etc. are used. In addition, it includes a polymer film and fiber that can be supplied in the form of a continuous roll, and may be used as a material made of paper, wood, metal, etc.

In the second step, a nickel oxide sol is made and coated on the plastic. Nickel oxide (NiO) primer uses nickel chloride. In addition, nickel acetate, nickel carbonate, nickel hydroxide, nickel nitrate, nickel sulfamate, nickel sulfate, nickel citrate, etc. may be used. In the case of nickel oxide coating, the band gap of anatase-type titanium oxide is 3.2 eV, but the band gap of nickel oxide is 4.0 eV. Separation by the energy level difference of titanium oxide increases the probability that holes will participate in a chemical reaction, thereby improving the photocatalytic efficiency by about two times or more. The solvents used in steps 2 and 4 include water, methanol, ethanol, isopropanol, 1-methoxypropanol, butanol, ethylhexyl alcohol, terpineol, ethylene glycol, glycerin, ethyl acetate, butyl acetate, and methoxypropyl. Acetate, carbitol acetate, ethyl carbitol acetate, methyl cellosolve, butyl cellosolve, diethyl ether, tetrahydrofuran, dioxane, methyl ethyl ketone, acetone, dimethylformamide, 1-methyl-2-pyrroly Any one or more selected from money, dimethyl sulfoxide, hexane, heptane, paraffin oil, mineral spirit, toluene, xylene, chloroform, and acetonitrile may be used. In addition, the method of coating the nickel oxide and titanium oxide precursor on the plastic in the second and fourth steps uses a three-roll coating. In addition, the coating, such as spray, three-roll coating, comma roll, gravure coating, three-roll coating, inkjet coating, knife coating, Mayer bar coating, etc. things are not limited

In the third step, immediately after coating the nickel oxide sol coated on the plastic, the liquid

state film is obtained. The coated nickel oxide sol is fired in a microwave. In this microwave irradiation, the microwaves uniformly irradiate the inside and the outside of the nickel oxide, so that the nickel oxide has a uniform temperature rise and the nickel oxide is fired to obtain a solid oxide type crystalline coating film. The primer having an inorganic structure irradiated with microwaves undergoes a hydrolysis condensation reaction between hydrolyzable groups over time when forming a coating film. can be formed This reaction does not affect the substrate when irradiating microwaves to the oxide precursor and further increases the crosslinking density, thereby obtaining a primer layer with excellent long-term weather resistance. However, since this microwave irradiation does not raise the temperature of the surface of the plastic, nickel oxide can be sintered without changing the plastic material. In addition, microwave irradiation for nickel oxide has good adhesion to plastics. The microwave irradiation device uses a microwave having a bandwidth of 300 MHz to 300 GHz. More preferably, a microwave having a bandwidth of 2.45 GHz is used. A photocatalyst-coated plastic manufacturing method, characterized by sintering a nickel oxide (NiO) primer and a titanium oxide (TiO) precursor with microwaves.

In the fourth step, a sol of titanium oxide is first made, and nano-particle titanium oxide is added therein. The addition of such nano-particle titanium oxide is to increase the surface area of the titanium oxide protruding to the outside. As the surface area protruding to the outside of the photocatalyst is wide, the efficiency of the photocatalyst is improved. In addition, the nanoparticles of titanium oxide are composed of a mixture of anatase and rutile type. Therefore, the rutile-type titanium oxide containing nanoparticles exhibits a photocatalytic effect even in some visible light. Here, as the nano titanium oxide particles, a mixture of anatase type and rutile type may be used, or anatase or rutile type may be used alone.

In the fifth step, titanium oxide sol containing nanoparticles on nickel oxide coated on plastic

Immediately after coating (sol), a liquid film is obtained. This coated titanium oxide sol

Firing with microwaves. Such microwave irradiation shows that the microwave

By uniformly irradiating the inside and the outside, the titanium oxide is uniformly heated, so that a solid oxide type crystalline coating film can be obtained by calcining the titanium oxide. However, since this microwave irradiation does not increase the temperature of the surface of the plastic, titanium oxide can be sintered without changing the plastic material.

4 is a decomposition reaction measurement of the two-layer structure photocatalyst according to the present invention prepared as described above.

As a graph showing the result, decomposition of methylorange, a type of dyeing wastewater

It is the result of evaluation by reaction. It can be seen that the decomposition reaction rate of the titanium oxide coating film including the nickel oxide-titanium oxide nanoparticles having a two-layer structure is significantly improved compared to the photocatalyst coated with only one layer of titanium oxide and nickel oxide coated with a primer and then coated with titanium oxide. have.

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