KR101657832B1 - Coated steel sheet using block polymer and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a process for preparing a polymer by carrying out a reversible addition-fragmentation chain transfer (RAFT) polymerization reaction of a first adduct, a chain transfer agent and an initiator. Supplying a second monomer and an initiator to the polymer to prepare a block copolymer; And coating a composition including the block copolymer on at least one surface of the steel sheet to form a coating layer. The method includes the steps of: preparing a coated steel sheet using a block copolymer; A smart coated steel sheet having the above properties can be produced.

Description

[0001] The present invention relates to a coated steel sheet using a block copolymer,

The present invention relates to a coated steel sheet using a block copolymer and a method for producing the same.

A block copolymer is a structure in which two or more polymer blocks are covalently linked to each other, and includes a diblock copolymer, a triblock copolymer, and the like. Because two or more blocks of different nature are chemically linked, phase separation occurs at a constant temperature and pressure, forming a nano-sized domain (microphase).

The shape and size of the domain formed at this time depends on the volume fraction (f), the molecular weight (N), and the mutual attraction coefficient (Flory-Huggins interaction parameter (χ)) among the constituents. In addition, when various external conditions (temperature, solvent, evaporation rate, relative humidity, substrate characteristics, etc.) are controlled during the formation of the domains, spheres, cylinders, A variety of structures including a gyroid and a lamellae are formed.

In recent years, besides the functions of basic protective coatings such as excellent surface sealing, antimicrobial, fingerprint and self-cleaning, there is a growing interest in smart-coated steel sheets with other functions. New coating materials such as nanoparticles and organic / inorganic composites have been studied to prepare these materials.

Photolithography can produce nanometer-scale fine patterns, but due to the nature of the technology, there are fundamental limitations such as dispersion of light and limitation of light source, and the process is complicated and the process operation cost is high. As an alternative to overcome this problem, the use of materials exhibiting self-assembly properties is emerging.

In order to solve the problems of the conventional method of manufacturing a nano-pattern, a method of manufacturing a coated steel sheet using a block copolymer having self-assembling properties is provided.

According to an embodiment of the present invention, there is provided a process for producing a polymer by reversibly addition-fragmentation chain transfer (RAFT) polymerization of a first donor, a chain transfer agent and an initiator. Supplying a second monomer and an initiator to the polymer to prepare a block copolymer; And coating a composition comprising the block copolymer on at least one surface of the steel sheet to form a coating layer.

And annealing the coating layer to form a self-assembled pattern of the block copolymer.

The annealing may be performed with a saturated solvent vapor.

The solvent may be at least one selected from toluene, acetone, benzene, ethanol, n-butanol, n-heptanol and isopropane.

The annealing may be performed at a temperature of 50 to 300 캜.

In the step of producing the polymer, the content ratio of the chain transfer agent and the initiator may be from 1: 0.01 to 0.5.

The initiator may be at least one selected from oxygen, hydroperoxides, peresters, percarbonates, peroxides, persulfates, and azo based initiators.

The first monomer may be polydimethylsioxane (PDMS), the second monomer may be N-vinylcarbazole (NVC), and the chain transfer agent may be a RAFT reagent.

The first monomer is N-vinylcarbazole, the second monomer is polydimethylsiloxane, and the chain transfer agent may be a switch-RATF reagent.

The composition may comprise from 0.5 to 2% by weight of the block copolymer and the remainder of the solvent.

The coating layer may be controlled to have a thickness of 0.1 to 10 mu m.

The coating is performed by a spin coating method, and the spin rate may be 1000 to 3000 rpm.

According to another embodiment of the present invention, And a coating layer formed on at least one surface of the steel sheet, wherein the coating layer provides a coated steel sheet using a block copolymer comprising a block copolymer.

The block copolymer may comprise a polydimethylsiloxane block and a poly N-vinylcarbazole block.

The weight ratio of the polydimethylsiloxane block and the poly N-vinylcarbazole block may be 1: 0.1 to 2.0.

The block copolymer may have a number average molecular weight of 500 to 30,000.

The block copolymer may have a spherical, cylinder, gyroid or lamellar structure.

The coating layer may have a thickness of 0.1 to 10 mu m.

The present invention provides a method for producing a coated steel sheet using a block copolymer, and can produce a smart coated steel sheet having a self-assembled pattern with a simple manufacturing process and a low operating cost.

Figure 1 is a schematic diagram of the RAFT polymerization mechanism.
2 is a schematic view of a reaction for synthesizing the block copolymer used in the present invention.
Fig. 3 is a photograph of the contact angle experiment of the steel sheet of Example 1; Fig.
Fig. 4 is a photograph of the contact angle experiment of the steel sheet of Example 2; Fig.
5 is a photograph of the contact angle experiment of the steel sheet of Comparative Example 1. Fig.
6 is a photograph of the contact angle experiment of the steel sheet of Comparative Example 2;

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

Since the block copolymer is composed of two or more different polymers connected by covalent bonds unlike the polymer used in the steel sheet coating, nano-sized phase separation phenomenon can be observed in the polymer blend or film. Further, a regular pattern can be obtained by controlling the molecular weight by the living radical polymerization method. These regular patterns can be used for various applications such as adhesion improvement, optical property control, lithography and surface property control, but examples applied to steel sheet coating are extremely limited.

In this study, we have synthesized block copolymers of polydimethylsioxane (PDMS) block with low surface energy and N-vinylcarbazole (NVC) block with conductivity property. Respectively.

Hereinafter, the method for producing the coated steel sheet of the present invention will be described in detail.

According to an embodiment of the present invention, there is provided a process for producing a polymer by reversibly addition-fragmentation chain transfer (RAFT) polymerization of a first donor, a chain transfer agent and an initiator. Supplying a second monomer and an initiator to the polymer to prepare a block copolymer; And coating a composition comprising the block copolymer on at least one surface of the steel sheet to form a coating layer.

The block copolymer to be applied to the coated steel sheet is prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, which is one of the living radical polymerization methods. The RAFT polymerization reaction has an advantage that the molecular weight can be kept constant, and RAFT agents and monomers required for RAFT polymerization are very important factors for the synthesis of block copolymers.

1 shows a schematic diagram of a RAFT polymerization reaction mechanism in which a radical (I) generated from an initiator (I) attacks a first monomer (M) in a reactor to generate a monomer or an oligomer radical (Pn) These radicals undergo a reversible chain transfer reaction with the chain transfer agent. At this time, R (leaving roup) easily falls off, a new initiation reaction proceeds, and the resulting oligomer radical can grow as a polymer by repeating addition and fragmentation reactions.

On the other hand, the Z group affects the reactivity of a group of C = S, which determines the rate at which the radicals are added and cleaved. The R group is cleaved in the form of radicals, and the re-initiation rate of the R group radicals to other monomers is preferably comparable to the initiation rate of existing radicals. Therefore, the chain transfer agent including the Z group and the R group is a factor that determines the speed of the reaction, so that selection of the type of chain transfer agent is very important.

According to one embodiment of the present invention, the first monomer is polydimethylsioxane (PDMS), the second monomer is N-vinylcarbazole (NVC), and the chain transfer agent is RAFT reagent desirable. FIG. 2 is a schematic view of a synthesis reaction of a block copolymer. PDMS and RAFT reagents react first to prepare a PDMS-RAFT reagent, and then react with NVC to prepare a block copolymer.

Also, the first monomer may be N-vinylcarbazole, the second monomer may be polydimethylsiloxane, and the chain transfer agent may be a switch-RATF reagent.

On the other hand, the initiator is preferably at least one selected from the group consisting of oxygen, hydroperoxide, perester, percarbonate, peroxide, persulfate, and azo based initiator, though it is not limited thereto.

The block copolymer prepared by the above-mentioned monomers, initiator and RATF reagent is a block copolymer comprising polydimethylsioxane (PDMS) block and poly-N-vinylcarbazole (NVC) block, The PDMS block with low surface energy and the conductive property correspond to the synthesis of block copolymer of NVC block.

The control of the molecular weight and composition of the block copolymer prepared through RAFT polymerization is important, and it can be determined by the ratio of the type of the monomer forming the block and the length of the block. Particularly, it is preferable to control the ratio since the content ratio of the chain transfer agent and the initiator affects the length of the block.

The content of the chain transfer agent and the initiator is preferably 1: 0.01 to 0.5, and if the content of the initiator is less than 0.01 times the content of the chain transfer agent, the content of the initiator is too small to initiate the reaction, If it exceeds 0.5 times, the content of the initiator becomes too much to remain in a radical form, which may deteriorate the physical properties.

On the other hand, it is preferable that the block copolymer has a number average molecular weight of 500 to 30,000, and if the number average molecular weight is less than 500, the block copolymer can not cover the coating layer properly so that physical properties are difficult to develop and a self- If it is 30,000 or more, the reaction rate is slow and the self-assembled layer can not be formed and the formation of the self-assembled layer can not be easily controlled.

The block copolymer prepared by the RAFT polymerization reaction may be included in a coating composition coating the steel sheet, and the composition may be coated on at least one surface of the steel sheet washed with acetone to form a coating layer.

If the content of the block copolymer is less than 0.5% by weight, a homogeneous self-assembled layer can not be formed on the substrate and more than 2% by weight of the block copolymer can be formed. The polymer self-assembled layer having fluidity can not be formed.

On the other hand, if the thickness is less than 0.1 탆, the coating layer is too thin, which can not properly manifest the characteristics of the self-assembled layer on the surface of the steel sheet and can be a barrier film for corrosion resistance If the thickness is more than 10 탆, the coating layer is too thick to form the self-assembled film uniformly. If the self-assembled film is a thick film, it is difficult to smoothly express the characteristics.

When the composition including the block copolymer is coated on the steel sheet, the coating method is not limited thereto, but may be performed by a spin coating method. Spin coating is one of the simplest methods of thin film deposition. Unlike other thin film manufacturing systems (eg, PLD, Sputtering, and CVD), expensive chambers and vacuum pumps are not required. Can be configured. In addition, it is possible to deposit all of the viscous solution in the solution state, and it is also advantageous to deposit a compound having a complex ternary system more than the desired composition.

If the spin speed is less than 1000 rpm, the coating layer may be too thick. If the spin speed is more than 3000 rpm, it is difficult to form a uniform coating layer.

The micro-worlds of the block copolymers coated on the steel sheet represent orientations that are oriented in a specific direction. In order to utilize the micro-world of the block copolymer in the manufacture of the self-assembled pattern, a technology capable of orienting the micro- .

Through the annealing of the coating layer containing the block copolymer, chains of the polymer constituting the block copolymer have sufficient mobility, so that the separation of the micro-world easily occurs, .

The formation of the self-assembled pattern can be performed by changing the temperature for a predetermined time using an annealing chamber. The coated substrate and the solvent may be put in the chamber and the reaction may proceed at a suitable temperature and a saturated solvent concentration atmosphere.

Particularly, when the annealing is carried out with a saturated solvent vapor, it is very effective in inducing the micro-world structure of the block copolymer and regulating the direction of the micro-world. Thus, the rate of solvent evaporation and the selectivity of the solvent to the block copolymer are the major factors controlling the microcrystallization of the block copolymer.

Therefore, the solvent is not particularly limited, but is preferably at least one selected from the group consisting of toluene, acetone, benzene, ethanol, n-butanol, n-heptanol and isopropane, Do. If the temperature is lower than 50 캜, sufficient annealing does not occur and the self-assembled pattern can not be formed properly. If the temperature exceeds 300 캜, the annealing proceeds too much and the fluidity of the self-assembled pattern may deteriorate.

By using the solvent vapor, a metastable state micro-structure can be obtained. In particular, since the direction in which the solvent is evaporated is always vertical, the solvent evaporates from the surface of the film and a slope of the solvent concentration is generated. A vertically aligned cylinder structure can be obtained, and a horizontally aligned cylinder can also be obtained by the solvent evaporation speed. On the other hand, this method has an advantage that it can be applied regardless of the substrate, and besides the method using the solvent vapor, the pattern can be produced by changing electric field, shear force, or surface property.

Hereinafter, the coated steel sheet of the present invention will be briefly described as being produced by the steel sheet producing method.

According to another embodiment of the present invention, And a coating layer formed on at least one surface of the steel sheet, wherein the coating layer provides a coated steel sheet using a block copolymer comprising a block copolymer.

The block copolymer may comprise a polydimethylsiloxane block and a poly N-vinylcarbazole block, and in particular, the content ratio of the polydimethylsiloxane block and the poly N-vinylcarbazole block may be 1: 0.1 To 2.0.

 The block copolymer may have a number average molecular weight of 500 to 30,000 and may have a spherical, cylinder, gyroid or lamellar structure.

 The thickness of the coating layer is preferably 0.1 to 10 mu m.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

One. Block copolymer  Produce

Synthesis Example 1

100 mL of dichloromethane and 0.183 g of DMAP were charged into a round flask and purged with nitrogen for 20 minutes. 40 mL of dichloromethane, 4.67 g of PDMS-OH, 0.619 g of DCC and 0.474 g of HOOC-RAFT were added to the reactor and reacted at 40 DEG C for 24 hours. After the reaction, the reaction product was cooled in a refrigerator for one day, and the solid matter was filtered out, and the remaining dechloromethane was removed using a rotary evaporator. This was followed by washing with excess methanol to remove unreacted RAFT-COOH, DCC and DMAP and drying to give a clear yellow material.

The yellow material, NVC and AIBN initiator were fed to a Schrange flask to perform RAFT polymerization. After mixing the RAFT agent, nitrogen purge is applied for 20 minutes and the mixture is maintained at 60-70 ° C for 30 hours. It was confirmed that the substance precipitated in the reactor corresponds to a block copolymer.

Synthesis Example 2

1000 mg of NVC monomer, 4.0 mg of AIBN and 9.3 mg of switch-RAFT were dissolved in 2.5 mL of dioxane, which was then placed in a round flask. After purging with nitrogen, reaction was carried out at 60 DEG C for 20 hours. When the reaction was completed, the reaction mixture was cooled to room temperature and then precipitated in hexane to obtain a precipitate.

300 mg of the precipitate, 0.736 mL of acrylic acid and 2-3 drops of concentrated hydrochloric acid were dissolved in 3 mL of dioxane, which was then transferred to a 25 mL round flask. After 2 hours of reaction at room temperature, the reaction was continued at 37 ° C for 2 hours. When the reaction was completed, the reaction mixture was cooled to room temperature, slowly added with an aqueous sodium chloride solution (0.5 M), and then diluted sulfuric acid aqueous solution was added. The resulting precipitate was filtered and then washed with water to prepare a block copolymer.

2. Block copolymer  Manufacture of steel sheet

The prepared block copolymer was supplied to water to prepare a coating solution. The content of the block copolymer and purified water was as shown in Table 1 below. The coating solution was coated on one side of the steel sheet by spin coating, and the spin rate was limited to 2000 rpm.

The steel sheet on which the coating layer was formed was put into the annealing chamber together with acetone, and then the temperature of the annealing chamber was controlled to 100 캜 to confirm the self-assembly pattern of the coating layer. Then, water droplets were dropped on the coated steel, and contact angle experiments were performed to confirm hydrophilic or hydrophobic characteristics. When the contact angle is in the range of 90 degrees or more and 50 degrees or less, it corresponds to a steel sheet exhibiting hydrophilic or hydrophobic properties.

division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Block copolymer (% by weight) - - One 2 Water (% by weight) - - 99 98 Contact Angle (°) 69 53 106 48

Comparative Example 1 and Comparative Example 2 correspond to a hot-dip galvanized steel sheet (GI) and an electroplated steel sheet (EG) not treated with the coating solution, and FIGS. 5 and 6 correspond to photographs of contact angle experiments of Comparative Examples 1 and 2 . In Comparative Examples 1 and 2, it was confirmed that the contact angle was 69 ° and 53 °, indicating no hydrophilic property or hydrophobic property.

On the other hand, Examples 1 and 2 correspond to a steel plate coated with a block copolymer, and Figs. 3 and 4 correspond to photographs of contact angle experiments of Examples 1 and 2. Since the contact angle of Example 1 was 106 deg. And the contact angle of Example 2 was 48 deg., It was confirmed that the steel sheet coated with the block copolymer exhibited hydrophilicity or hydrophobicity.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (18)

Preparing a polymer by a reversible addition-fragmentation chain transfer (RAFT) polymerization reaction of a first donor, a chain transfer agent and an initiator;
Supplying a second monomer and an initiator to the polymer to prepare a block copolymer; And
And coating a composition comprising the block copolymer on at least one side of the steel sheet to form a coating layer,
Wherein the block copolymer comprises a polydimethylsiloxane block and a poly N-vinylcarbazole block.
The method of claim 1, further comprising the step of annealing the coating layer to form a self-assembly pattern of the block copolymer.
3. The method of claim 2, wherein the annealing is performed with a saturated solvent vapor.
4. The method according to claim 3, wherein the solvent is at least one selected from the group consisting of toluene, acetone, benzene, ethanol, n-butanol, n-heptanol and isopropane.
The method of claim 2, wherein the annealing is performed at a temperature of 50 to 300 캜.
The method for producing a coated steel sheet according to claim 1, wherein, in the step of producing the polymer, the content ratio of the chain transfer agent and the initiator is 1: 0.01 to 0.5.
The method of claim 1, wherein the initiator is at least one block copolymer selected from oxygen, hydroperoxide, perester, percarbonate, peroxide, persulfate, and azo based initiator.
The method of claim 1, wherein the first monomer is polydimethylsioxane (PDMS), the second monomer is N-vinylcarbazole (NVC), and the chain transfer agent is a block copolymer that is a RAFT reagent A method of manufacturing a coated steel sheet using the method.
The method of claim 1, wherein the first monomer is N-vinylcarbazole, the second monomer is polydimethylsiloxane, and the chain transfer agent is a switch-RATF reagent.
The method of claim 1, wherein the composition is a block copolymer comprising 0.5 to 2% by weight of a block copolymer and the balance solvent.
The method of claim 1, wherein the coating layer is controlled to have a thickness of 0.1 to 10 탆.
The method of claim 1, wherein the coating is performed by a spin coating method and the spin rate is 1000 to 3000 rpm.
Steel plate; And
And a coating layer formed on at least one surface of the steel sheet,
Wherein the coating layer comprises a block copolymer comprising a polydimethylsiloxane block and a poly N-vinylcarbazole block.
delete 14. The coated steel sheet according to claim 13, wherein the weight ratio of the polydimethylsiloxane block and the poly N-vinylcarbazole block is 1: 0.1 to 2.0.
14. The coated steel sheet according to claim 13, wherein the block copolymer has a number average molecular weight of 500 to 30,000.
14. The coated steel sheet according to claim 13, wherein the block copolymer is a block copolymer having a spherical, cylinder, gyroid or lamellar structure.
14. The coated steel sheet according to claim 13, wherein the coating layer is a block copolymer having a thickness of 0.1 to 10 mu m.

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