KR20200052644A - Manufacturing method of hydrophilic zinc flake using silane coupling reaction - Google Patents

Abstract

Disclosed is a method for manufacturing hydrophilic zinc flakes using silane coupling reaction and, more specifically, to a method comprising: a hydrolysis step of hydrolyzing silane; a raw material mixing step of mixing the silane, hydrolyzed through the hydrolysis step, and zinc flake slurry; a milling step of milling the mixture manufactured through the raw material mixing step; and a dehydrating and drying step of dehydrating and drying the mixture milled through the milling step. In the hydrophilic zinc flakes manufactured through the above steps, a silane coating layer is formed to suppress oxidation reaction in water-based paint or coating solutions, dispersibility and storage stability are increased, and when applied to a metal material such as iron, can be stably dispersed or stored in the solution while maintaining the electrochemical anticorrosive functions of zinc.

Description

Manufacturing method of hydrophilic zinc flakes using silane coupling reaction {MANUFACTURING METHOD OF HYDROPHILIC ZINC FLAKE USING SILANE COUPLING REACTION}

The disclosed content relates to a method for producing a hydrophilic zinc flake using a silane coupling reaction, and more specifically, a silane coating layer is formed to suppress an oxidation reaction in a water-based paint or coating solution, improve dispersibility and storage stability, and improve iron. When applied to a metal material such as zinc, while maintaining the electrochemical anticorrosive function, it relates to a method of manufacturing a hydrophilic zinc flake using a silane coupling reaction that can be stably dispersed or stored in an aqueous solution.

The water-soluble chromic acid-zinc powder coating method, which was first developed in the United States in 1974, has been applied to various industrial fields today instead of electric and hot-dip galvanizing due to its high corrosion resistance and material adhesion. It has been introduced in Korea since 1982, and has been applied to many fields such as automobile parts, fastener parts such as bolts, nuts and hose clips, electrical and electronics, and construction materials.

The surface treatment technology mainly included in the finishing process is an important process for determining the surface properties, durability, and appearance, and especially in the case of automobiles, the plating and coating equipment rate reaches about 10%, and the surface treatment technology and Advancement of metal pigment powder is an important technical factor directly related to the improvement of quality in the final industry.

The most important pigment used in the water-soluble chromic acid-zinc powder coating agent is unoxidized zinc flake powder, which has an average particle size of 4 to 6㎛ round type zinc dust. Is manufactured by milling. In the case of zinc, it is a metal in the ionization tendency sequence that is faster than iron, and when applied to the surface of iron, it is electrochemically oxidized to become an anode (sacrificial anode function) and serves to prevent corrosion of iron through this. The anti-corrosion performance by the anode function is an irreplaceable material in terms of price and effect, and has been widely used as a corrosion-resistant material for a long time.

The water-soluble chromic acid-zinc powder coating agent is used by coating thinly with a thin film of 10 µm or less on the surface of parts requiring corrosion protection. These products have a 20% or more improvement in corrosion resistance compared to electro-galvanized plating, which can reduce costs by more than 10%. It is known.

In addition, compared to the existing plating method that generates a large amount of waste water, the amount of waste water is less, and it is a product that can significantly reduce the amount of environmental pollutants such as VOC (volatile organic compound) as a water-soluble coating agent. It is widely used in about 270 parts, home appliance parts such as washing machines, refrigerators, TVs, etc., and such anticorrosive coating treatments are widely applied to construction and civil engineering equipment parts.

Water-soluble anti-corrosive paints have many advantages over oil-based paints for reasons such as atmospheric environment and worker safety, but in the case of zinc powder, the main raw material of water-soluble anti-corrosive paints, storage stability is reduced through oxidation reaction with water (water). There is this. Therefore, to date, anti-corrosive coatings or coating solutions using zinc have been mainly used as solvent-based coatings or mixed oil / water-based coating solutions. Recently, water-soluble anti-corrosive coatings or water-soluble coatings have been used due to environmental problems such as VOC problems and safety issues for workers. The demand for coating liquids is gradually increasing. Moreover, recently, more and more companies are producing water-soluble rust preventive paints or water-soluble anticorrosive coating solutions using a flake zinc powder with a large surface area and a structurally high anti-corrosive effect compared to spherical zinc powder. However, in order to be used in such a water-based coating or coating solution, the storage stability due to the generation of hydrogen gas due to the reaction of the metal zinc powder and water, and the problem of poor coating and poor adhesion performance must be improved.

Korean Patent Registration No. 10-1797116 (2017.11.07)

The disclosed content is that a silane coating layer is formed to suppress oxidation reaction in water-based paints or coating liquids, improve dispersibility and storage stability, and maintain the electrochemical anticorrosive function of zinc as it is applied to metal materials such as iron, while maintaining an aqueous solution. It is to provide a method for producing a hydrophilic zinc flake using a silane coupling reaction that can be stably dispersed or stored therein.

In one embodiment, the contents of this disclosure include a hydrolysis step of hydrolyzing silane, a raw material mixing step of mixing the hydrolyzed silane through the hydrolysis step with a zinc slurry, and a mixture prepared through the raw material mixing step. It describes a method of manufacturing a hydrophilic zinc flake using a silane coupling reaction, characterized in that consisting of a milling step of milling and a dehydration drying step of dehydrating and drying the mixture milled through the milling step.

Preferably, the hydrolysis step may be made for 1 to 6 parts by weight of silane in 100 parts by weight of ethanol, and may be performed for 10 to 60 minutes at a temperature of 30 to 70 ° C and a rate of 100 to 150 rpm.

More preferably, the silane is 2- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxy silane, trimethyl fluoro silane, triethylsilane, ethyltrimethyl Silane, triisopropyl silane, 3-amino propyl triethoxy silane, 3-amino propyl trimethoxy silane, 3-amino propyl methyl diethoxy silane, 3-amino propyl methyl dimethoxy silane, amino ethyl amino propyl tri Methoxy silane, diethyl amino methyl triethoxy silane, diethyl amino methyl triethoxy silane, diethyl amino propyl triethoxy silane, N- (N-butyl) -3-amino propyl trimethoxy silane, 3- Glossyoxypropyl trimethoxy silane, 3-Glyoxydoxy propyl methyl diethyl silane, 3-Glyoxydoxy propyl methyl dimethoxy silane, 2- (3,4-epoxycyclohexyl) -ethyl trimethoxy silane, 3-mer Capto Propyl trimethoxy silane, 3-mercapdo propyl triethoxy silane, 3-mercapto propylmethyl dimethoxy silane, tetramethoxy silane, and derivatives thereof.

More preferably, the raw material mixing step is mixing 1 to 3 parts by weight of silane hydrolyzed through the hydrolysis step compared to 100 parts by weight of zinc mixed in the zinc slurry, and for 20 to 30 minutes at a rate of 200 to 500 rpm It can be achieved by stirring.

Even more preferably, the zinc slurry may be prepared by mixing 25 to 50 parts by weight of zinc powder with 100 parts by weight of alcohol.

Even more preferably, the milling step may be performed for 60 to 180 minutes at a speed of 1000 to 2000 rpm using a high energy ball mill.

Even more preferably, in the dehydration drying step, the mixture milled through the milling step may be dehydrated and vacuum dried to adjust the moisture content to 0.3 mass% or less.

In the method for producing a hydrophilic zinc flake using a silane coupling reaction as described above, a silane coating layer is formed to suppress an oxidation reaction in a water-based paint or coating solution, improve dispersibility and storage stability, and apply to metal materials such as iron. When it does, it maintains the electrochemical anticorrosive function of zinc, and exhibits an excellent effect of providing zinc flakes that can be stably dispersed or stored in an aqueous solution.

1 is a flow chart showing a method of manufacturing a hydrophilic zinc flake using the disclosed silane coupling reaction.
2 is a view showing a silane coupling process in which a silane coating layer is formed on the surface of zinc.
3 is a view showing a hydrogen gas measuring apparatus using the upward displacement method.
4 is a graph showing the measurement of the hydrogen gas generation inhibitory effect of the components prepared through the disclosed Examples 1 to 2 and Comparative Examples 1 to 2.
5 is a photograph showing the thickness of the silane coating layer formed on the surface of the hydrophilic zinc flake prepared through Preparation Example 2 by transmission electron microscopy (TEM).
FIG. 6 is a photograph showing the appearance of circular zinc powder and flake zinc powder by scanning electron microscope (SEM) d.

Hereinafter, the preferred embodiment of the present invention and the physical properties of each component will be described in detail, but it is intended to be described in detail so that a person skilled in the art to which the present invention pertains can easily implement the invention. This does not mean that the technical spirit and scope of the present invention is limited.

Disclosed is a method for manufacturing a hydrophilic zinc flake using a silane coupling reaction, a hydrolysis step (S101) of hydrolyzing silane, and a raw material mixing step of mixing the hydrolyzed silane through the hydrolysis step in the zinc slurry. (S103), a milling step (S105) of milling the mixture prepared through the raw material mixing step and a dehydration drying step (S107) of dehydrating and drying the mixture milled through the milling step (S105).

The hydrolysis step (S101) is a step of hydrolyzing silane, mixing 1 to 6 parts by weight of silane with 100 parts by weight of ethanol, and hydrolyzing at a temperature of 30 to 70 ° C and a rate of 100 to 150 rpm for 10 to 60 minutes. In this step, at this time, the content of the silane may contain 1 to 6 parts by weight compared to 100 parts by weight of ethanol, but more preferably contains 1 to 3 parts by weight, the reaction temperature can be made to a temperature of 30 to 70 ℃ However, considering the rate of hydrolysis, loss due to subsequent reaction, and the like, it is more preferably made of 50 to 60 ° C.

In addition, the agitation speed is 100 to 150 rpm, and when the agitation speed is less than 100 rpm, the hydrolysis reaction efficiency of silane decreases, and when the agitation speed exceeds 150 rpm, the rate of formation of side reaction products by a subsequent reaction increases. .

At this time, the silane is 2- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxy silane, trimethyl fluor silane, triethylsilane, ethyltrimethyl silane, tri Isopropyl silane, 3-amino propyl triethoxy silane, 3-amino propyl trimethoxy silane, 3-amino propyl methyl diethoxy silane, 3-amino propyl methyl dimethoxy silane, amino ethyl amino propyl trimethoxy silane , Diethyl amino methyl triethoxy silane, diethyl amino methyl triethoxy silane, diethyl amino propyl triethoxy silane, N- (N-butyl) -3-amino propyl trimethoxy silane, 3-glycidoxy propyl Trimethoxy silane, 3-glycidoxy propyl methyl diethyl silane, 3-glycidoxy propyl methyl dimethoxy silane, 2- (3,4-epoxycyclohexyl) -ethyl trimethoxy silane, 3-mercapto propyl triIt is preferably composed of at least one selected from the group consisting of methoxy silane, 3-mercapdo propyl triethoxy silane, 3-mercapto propylmethyl dimethoxy silane, tetramethoxy silane and derivatives thereof, and 2- (3, It is more preferable to consist of 4-epoxycyclohexyl) -ethyltrimethoxysilane or 3-glycidoxypropyl trimethoxysilane.

The raw material mixing step (S103) is a step of mixing the hydrolyzed silane through the hydrolysis step (S101) to the zinc slurry, through the hydrolysis step (S101) compared to 100 parts by weight of zinc mixed with the zinc slurry. It is made by mixing 1 to 3 parts by weight of hydrolyzed silane and stirring for 20 to 30 minutes at a rate of 200 to 500 rpm, which is hydrolyzed through the hydrolysis step (S101) on the surface of the zinc powder contained in the zinc slurry. It is desirable to stir so that the silane is sufficiently wetting.

At this time, if the stirring speed is less than 200 rpm or the stirring time is less than 20 minutes, the silane hydrolyzed through the hydrolysis step (S101) is not sufficiently wetting on the surface of the zinc powder contained in the zinc slurry, and the stirring speed is 500 rpm. If exceeded or the stirring time exceeds 30 minutes, the process may be disturbed due to excessive air bubbles, and the process efficiency is reduced.

In addition, the zinc slurry is prepared by mixing zinc dust, a raw material with a solvent such as alcohol, in a slurry form for use in mass flow and mass production of the material required in the manufacture of flake zinc powder. It is preferable to prepare by mixing 25 to 50 parts by weight of powder.

The milling step (S105) is a step of milling the mixture prepared through the raw material mixing step (S103), and is performed for 60 to 180 minutes at a speed of 1000 to 2000 rpm using a ball mill. After passing through step S105, a zinc flake in which the silane coating layer is uniformly formed to 50 nanometers or less may be provided through a coupling reaction on the surface of zinc contained in the zinc sludge.

At this time, the milling may be performed using various milling equipment such as an Attrition mill, High energy ball mill, Jet mill, and it is most preferable to use a horizontal high energy ball mill.

The horizontal high-energy ball mill is the most widely used equipment for metal powder processing due to the price of equipment and the convenience of operation. In particular, it has a higher rotational speed (pressure due to centrifugal force) than a general ball mill, and yields compared to an attrition mill. This is high. In addition, compared to jet mills, Zoz mills, etc., the equipment price and additional cost are cheaper, and the flattening processing area is wider due to the horizontal type, and production time can be shortened.

In addition, the rotational speed in the milling step (S105) is 1000 to 2000 rpm, and it is more preferable to perform high-speed stirring at a speed of 1400 to 1800 rpm. If the rotational speed is less than 1000 rpm, the thickness of the silane coating layer is formed to 100 nm or more. If the rotational speed exceeds 2000 rpm, it is difficult to form a silane coating layer.

In addition, the time of the milling step (S105) is made for 60 to 180 minutes, more preferably 90 to 120 minutes, if the time of the milling step (S105) is less than 60 minutes, the production yield of zinc flakes is lowered , When the time of the milling step (S105) exceeds 180 minutes, the viscosity of the raw material is excessively increased due to the increase in the internal temperature and pressure of the mill, resulting in aggregation between materials.

The silane coupling process in which a silane coating layer is formed on the surface of zinc is shown in FIG. 2 below. As shown in Figure 2 below, the silicon functional group (X. silicon functional group) of the hydrolyzed silane is combined with a hydroxyl group on the surface of zinc, which is a metal material, and the organic functional group is organic in an aqueous solution. It is combined with the binder component to maintain a stable state in the aqueous solution. As described above, the oxidation reaction of the zinc powder can be suppressed through the formation of a silane coating layer through a coupling reaction on the metal surface, and when a dry coating film is formed after mixing with a water-soluble binder, the metal zinc surface has a sacrificial anode function. It becomes possible to perform the electrochemical method.

In addition, in order to impart hydrophilicity to a metal zinc powder in a water-soluble coating and coating solution, a coupling reaction between a silane and a metal zinc powder surface must be appropriately induced. In general, the metal zinc powder is made of iron (Fe). When coated on the surface of the material, it has electrochemical anti-corrosion performance through the sacrificial anode function of zinc. However, when applied as a pigment to a water-soluble paint or coating agent, zinc (Zn) is oxidized to zinc oxide (ZnO) as shown in Reaction Scheme 1 below to generate a large amount of hydrogen gas (H ₂ gas). Oxidation reaction of zinc dust, which is a metal in water-soluble paint or coating solution, causes many problems such as deterioration of storage stability, corrosion of pinholes, deterioration of adhesion, and occurrence of blisters. To date, there is no complete water-soluble anticorrosive coating or coating solution using zinc powder.

Therefore, in the disclosed contents, silane is added during the manufacturing process of zinc flake powder, which has excellent anticorrosive performance in comparison with zinc dust, in order to solve these problems, and zinc surface through high-speed stirring during milling. By inducing a coupling reaction of silane in the silane thin film coated flake zinc powder of 50 nanometers or less can be provided. Through the preparation of the silane-coated flake zinc powder, the oxidation reaction of zinc in the water-based coating or coating solution can be delayed or suppressed, and the dispersibility and storage stability of the flake zinc can be increased. In addition, when a hydrophilic silane coating layer of 50 nanometers or less is formed and applied to the surface of iron, the electrochemical anticorrosive function of zinc is maintained while providing a water-soluble anticorrosive coating solution that can be stably dispersed or stored in an aqueous solution. There will be.

<Reaction Scheme 1> Oxidation of zinc in aqueous solution

(g)

(g)

The dehydration and drying step (S107) is a step of dehydrating and drying the mixture milled through the milling step (S105), and dehydrating the mixture milled through the milling step (S105) and vacuum drying the water content to 0.3% by mass. This is the step of adjusting below.

Hereinafter, a method of manufacturing a hydrophilic zinc flake using the disclosed coupling reaction and the physical properties of the hydrophilic zinc flake produced through the manufacturing method will be described with reference to examples.

<Production Example 1> Preparation of hydrolyzed silane

Mix 3.5 parts by weight of silane {2- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane} to 100 parts by weight of ethanol, and stir for 35 minutes at a temperature of 50 ° C and a rate of 125 rpm for hydrolyzed silane. It was prepared.

<Production Example 2> Preparation of hydrophilic zinc flakes

The mixture prepared by mixing 1 part by weight of hydrolyzed silane prepared through Preparation Example 1 to 100 parts by weight of zinc mixed in zinc slurry (100 parts by weight of alcohol and 37.5 parts by weight of zinc powder) was mixed for 25 minutes at a rate of 350 rpm. Stirring and forming a silane coating layer on the surface of zinc through a coupling reaction in which the stirred mixture is milled for 115 minutes at a speed of 1500 rpm using a horizontal high energy ball mill, and the mixture containing zinc on which the silane coating layer is formed is formed. Dehydrated, put in a vacuum drying apparatus and dried to prepare a hydrophilic zinc flake.

<Production Example 3> Preparation of hydrophilic zinc flakes

Proceeding in the same manner as in Preparation Example 2, a hydrophilic zinc flake was prepared by mixing 3 parts by weight of hydrolyzed silane.

<Example 1>

A mixture was prepared by mixing 60% by weight of ethanol, 10% by weight of distilled water, and 30% by weight of hydrophilic zinc flakes prepared through Preparation Example 2.

<Example 2>

A mixture was prepared by mixing 60% by weight of ethanol, 10% by weight of distilled water, and 30% by weight of hydrophilic zinc flakes prepared through Preparation Example 3.

<Comparative Example 1>

Distilled water.

<Comparative Example 2>

A mixture was prepared by mixing 60% by weight of ethanol, 10% by weight of distilled water, and 30% by weight of zinc flakes.

The hydrogen gas generation inhibitory effect of the components prepared through Examples 1 to 2 and Comparative Examples 1 to 2 was measured and shown in FIG. 4 below.

{However, the effect of inhibiting the generation of hydrogen gas is hydrogen over time through a hydrogen gas measuring apparatus using the upward displacement method as shown in FIG. 3 below for the components prepared through Examples 1 to 2 and Comparative Examples 1 to 2 A method for measuring the amount of gas generated was used.

At this time, the experiment was conducted at room temperature (25 ° C) and high temperature (60 ° C), respectively. To test the amount of hydrogen generated at high temperature, dip the Erlenmeyer flask into which the material is mixed in a constant temperature water tank and set the temperature of the constant temperature water tank to 60 ° C. Proceeded. Through the hydrogen generation amount measurement experiment at room temperature and high temperature, the efficiency of hydrogen gas reduction according to the storage environment of the water-soluble anticorrosive coating solution mixed with zinc flakes was evaluated. In the case of hydrogen gas, it is a gas that has low solubility in water and is lighter than air, so it is possible to measure the volume by the upward displacement method, and the hydrogen gas collection container is made to use a measuring cylinder to facilitate volume measurement over time.}

As shown in FIG. 4 below, as a result of measurement at room temperature (25 ° C.), it can be seen that in Example 1, hydrogen gas is reduced by 50 to 80% compared to Comparative Example 2.

In addition, it can be seen that in Examples 1 to 2, compared with Comparative Example 1 in which zinc flakes were not contained, about 10% of hydrogen gas was generated, indicating stable storage in an aqueous solution.

In addition, it can be seen that in the case of high temperature (60 ° C.), the amount of hydrogen gas generated is reduced by 65% in Example 1 and 72% in Example 2 compared to Comparative Example 2 in which the silane is not coated.

In addition, the thickness of the silane coating layer formed on the surface of the hydrophilic zinc flake prepared through Preparation Example 2 was photographed with a Transmission Electron Microscope (TEM) and is shown in FIG. 5 below.

As shown in FIG. 5 below, it can be seen that the hydrophilic zinc flake prepared through Example 1 disclosed has a silane coating layer uniformly coated within 20 to 50 nanometers.

Therefore, in the method for producing a hydrophilic zinc flake using the disclosed silane coupling reaction, a silane coating layer is formed to suppress an oxidation reaction in a water-based paint or coating solution, improve dispersibility and storage stability, and apply to metal materials such as iron. When the electrochemical anticorrosive function of zinc is maintained, zinc flakes that can be stably dispersed or stored in an aqueous solution can be provided.

S101; Hydrolysis step
S103; Raw material mixing step
S105; Milling stage
S107; Dehydration drying step

Claims (7)

A hydrolysis step of hydrolyzing silane;
A raw material mixing step of mixing the zinc slurry with silane hydrolyzed through the hydrolysis step;
Milling step of milling the mixture prepared through the raw material mixing step; And
Dehydration and drying step of dehydrating and drying the mixture milled through the milling step; Method for producing a hydrophilic zinc flake using a silane coupling reaction.
The method according to claim 1,
The hydrolysis step is a hydrophilic zinc using a silane coupling reaction characterized in that 1 to 6 parts by weight of silane is mixed with 100 parts by weight of ethanol, and is performed at a temperature of 30 to 70 ° C and a rate of 100 to 150 rpm for 10 to 60 minutes. Method of manufacturing flakes.
The method according to claim 1 or 2,
The silane is 2- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, 3-glycidoxypropyl trimethoxy silane, trimethyl fluoro silane, triethylsilane, ethyltrimethyl silane, triisopropyl Silane, 3-amino propyl triethoxy silane, 3-amino propyl trimethoxy silane, 3-amino propyl methyl diethoxy silane, 3-amino propyl methyl dimethoxy silane, amino ethyl amino propyl trimethoxy silane, di Ethyl amino methyl triethoxy silane, diethyl amino methyl triethoxy silane, diethyl amino propyl triethoxy silane, N- (N-butyl) -3-amino propyl trimethoxy silane, 3-glycidoxy propyl trime Thoxy silane, 3-glycidoxy propyl methyl diethyl silane, 3-glycidoxy propyl methyl dimethoxy silane, 2- (3,4-epoxycyclohexyl) -ethyl trimethoxy silane, 3-mercapto propyl trimethoxy Silane, 3-mercapdo propyl triethoxy silane, 3-mercapto propylmethyl dimethoxy silane, tetra methoxy silane, and derivatives thereof using one or more selected from the group consisting of silane coupling reaction using Method for manufacturing hydrophilic zinc flakes.
The method according to claim 1,
The raw material mixing step is characterized by mixing 1 to 3 parts by weight of silane hydrolyzed through the hydrolysis step compared to 100 parts by weight of zinc mixed in the zinc slurry, and stirring for 20 to 30 minutes at a rate of 200 to 500 rpm. Method for producing a hydrophilic zinc flake using a silane coupling reaction.
The method according to claim 4,
The zinc slurry is a method for producing a hydrophilic zinc flake using a silane coupling reaction, characterized in that it is prepared by mixing 25 to 50 parts by weight of zinc powder with 100 parts by weight of alcohol.
The method according to claim 1,
The milling step is a method for producing a hydrophilic zinc flake using a silane coupling reaction, characterized in that it is performed for 60 to 180 minutes at a speed of 1000 to 2000 rpm using a high energy ball mill.
The method according to claim 1,
The dehydration and drying step is a method for producing a hydrophilic zinc flake using a silane coupling reaction characterized in that the mixture milled through the milling step is dehydrated and dried in vacuo to adjust the moisture content to 0.3% by mass or less.

Images