KR102149688B1 - Pearlescent pigment particle and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to pearly luster pigment particles, and a method for producing the same. While different metal oxide layers are formed at a coating part coated on a base material, a rutile crystal structure can be easily formed, and the thickness of the coating layer can be easily adjusted. The method for producing pearly luster pigment particles according to an embodiment of the present invention is a method for producing pearly luster pigment particles on which a coating part formed with a plurality of layers is formed on the surface of the base material, and comprises: a first step of preparing a baes material; a second step of preparing a precursor for forming a coating part; and a third step of forming a coating part on the surface of the base material, wherein the thickness of at least one of a plurality of layers for forming the coating part is adjusted by using a titration technique, and a layer composed of metal oxide is formed while the thickness is adjusted.

Description

Pearlescent pigment particle and manufacturing method thereof

The present invention relates to pearlescent pigment particles and a method for producing the same, and more particularly, it is possible to easily form a rutile crystal structure while forming different metal oxide layers on the coating portion coated on the substrate, and It relates to pearlescent pigment particles capable of easily adjusting the thickness and a method of manufacturing the same.

Pearlescent pigment refers to a pigment that expresses apricot, iridescent, metallic, etc.

A typical pearlescent pigment has a structure in which nano-sized metal oxide fine particles are densely coated on mica in the form of flakes having a micro size. At this time, the particle size of the mica particles used is adjusted according to the type of pearlescent pigment, and should be maintained at 0.1 ~ 200㎛. This is because if the mica particles are too small, light scattering occurs a lot, resulting in poor gloss, and if the particles are too large, there are restrictions on use. Therefore, the pearlescent pigments commonly used have a mica thickness of 0.1 to 10 μm, and the thickness of a coating layer formed of metal oxide fine particles is 10 to 150 nm.

Meanwhile, examples of metal oxides used in pearlescent pigments include Ti0 ₂ , Si0 ₂ , ZnO, and W0 ₃ . In addition, CdS and ZnS may be used instead of the metal oxide. At a refractive index of 500 to 600 nm, the refractive index of Ti0 ₂ is 2.84, the refractive index of Si0 ₂ is 1.457, the refractive index of ZnO is 2.0, the refractive index of W0 ₃ is 1.67, the refractive index of CdS is 2.384, and the refractive index of ZnS is 2.355 to be. Therefore, a pearlescent pigment having a predetermined refractive index is produced by coating the material on the surface of the mica as a substrate using a material exhibiting a desired refractive index.

A typical metal oxide used in pearlescent pigments is Ti0 ₂ , and the crystal structure of Ti0 ₂ can be divided into rutile, anatase, and brookite. Among them, Burookite is very unstable and is not used industrially because it is difficult to synthesize pure crystals, and Ti0 ₂ having a crystal structure of Rutile and Anatase is used industrially.

In the case of anatase crystal structure, it is mainly used as a photocatalyst because of its excellent photoactivity. Recently, it is widely used for air cleaning. In contrast, the rutile (Rutile) crystal structure is generally used as a white pigment because of its excellent light resistance and heat resistance. On the other hand, the anatase crystal structure has a characteristic that a phase transition occurs when it receives heat in the process of coating Ti0 ₂ , and the crystal structure changes to rutile. In terms of pigment's physical properties, Ti0 ₂ has superior light resistance, heat resistance, and weather resistance compared to the anatase crystal structure, has good color and hiding power, and has a high refractive index. It is advantageous that TiO ₂ having a rutile crystal structure is used.

In addition, Ti0 ₂ has good optical properties and is known to be harmless to the human body, as well as good corrosion resistance and mechanical durability. In addition, since the refractive index ranges from 1.9 to 2.6 depending on the deposition type, a high refractive index can be utilized when coated on mica. In particular, since Ti0 ₂ having a rutile crystal structure is transparent and birefringent, it is advantageous to form a rutile crystal structure for use as a pearlescent pigment. However, when Ti0 ₂ is coated on mica under general coating process conditions, there is a disadvantage that it is coated with an anatase crystal structure.

On the other hand, a method of coating Ti0 ₂ on a substrate such as mica is mainly a fluidized bed chemical vapor deposition method and a uniform precipitation method.

First, the fluidized bed chemical vapor deposition method is a method of coating a gaseous raw material on a substrate (mica) to be coated.

When Ti0 ₂ is coated on a substrate (mica) by using a chemical vapor deposition method, a reaction as shown in Formula 1 below occurs.

TiCl ₄ + 2H ₂ O + Mica (mica) → TiO ₂ -Mica + 4HCl… [Formula 1]

However, in the case of using the fluidized bed chemical vapor deposition method, TiO ₂ coated on the substrate is formed in an anatase crystal structure. Therefore, in order to phase change the anatase crystal structure of TiO ₂ to a rutile crystal structure, during the coating process SnO ₂ should be added. However, to the addition of SnO ₂ to induce a phase transition of the TiO ₂ it has a limit in commercial use in a fluidized bed chemical vapor deposition because it must heat the titanium tetrachloride (TiCl ₄₎ at a high temperature.

In addition, the homogeneous precipitation method is a method of releasing OH ^- ions through a solution reaction such as hydrolysis without adding a precipitant to the solution when precipitation is generated, thereby causing precipitation.

When Ti0 ₂ is coated on a substrate (mica) using a homogeneous precipitation method, a reaction as shown in Formula 2 below occurs.

TiOSO ₄ + Mica + H ₂ O → TiO ₂ -Mica + H ₂ SO ₄ … [Formula 2]

In the case of using the homogeneous precipitation method, when a titanium salt solution is added and stirred while applying a constant temperature to ultrapure water including mica, the titanium salt is hydrolyzed to form a precipitate and the titanium hydrate is coated on the surface of the mica. However, since the homogeneous precipitation method exhibits strong acidity during the reaction process, it is necessary to neutralize the pH for safety. In addition, in the case of using the uniform precipitation method, since TiO ₂ to be precipitated has an elliptical irregular shape, light scattering is caused by the shape, which causes a decrease in the pearlescent effect.

The content described above as the background art is only for understanding the background of the present invention, and should not be taken as an acknowledgment that it corresponds to the prior art already known to those of ordinary skill in the art.

Registered Patent Publication No. 10-1858414 (2013.05.09)

The present invention provides a pearlescent pigment particle capable of easily forming a rutile crystal structure even at a low temperature by using SnO when Ti0 ₂ is coated on a substrate, and a method for producing the same.

In addition, the present invention provides a pearlescent pigment particle capable of easily adjusting the thickness of the coating layer by coating Ti0 ₂ using a titration method without using a fluidized bed chemical vapor deposition method or a uniform precipitation method, and a method for manufacturing the same. .

Pearlescent pigment particles according to an embodiment of the present invention comprises a substrate; Doedoe coated on the surface of the substrate, and includes a coating formed by coating at least two different metal oxides in stages.

The coating unit may include a first metal oxide layer coated on the surface of the substrate; A second metal oxide layer coated on the surface of the first metal oxide layer; And a protective layer coated on the surface of the second metal oxide layer.

The substrate is mica of flakes, the coating part, the first metal oxide layer is formed of tin oxide (SnO) having a rutile crystal structure, and the second metal oxide layer is a rutile crystal The structure is formed of titanium dioxide (TiO ₂ ), and the protective layer is characterized in that it is formed of sodium silicate (Na ₂ SiO ₃ ).

The coating part is formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the protective layer, and a third metal oxide layer formed with a thickness different from that of the second metal oxide layer is further formed. It is characterized.

The second metal oxide layer and the third metal oxide layer have a thickness of 10 to 150 nm, respectively.

On the other hand, the method for producing pearlescent pigment particles according to an embodiment of the present invention is a method of manufacturing pearlescent pigment particles in which a coating portion formed in a plurality of layers is formed on the surface of a substrate, comprising a first step of preparing a substrate and ; A second step of preparing a precursor for forming a coating; Forming a coating on the surface of the substrate, wherein at least one of the plurality of layers forming the coating includes a third step of forming a layer made of metal oxide while adjusting its thickness using a titration method. .

In the first step, the substrate is prepared as a thin flake having a thickness of 0.1 to 10 μm using natural mica or synthetic mica, and in the second step, the precursor is tin oxide forming a first metal oxide layer ( It is characterized in that it comprises a SnO) precursor and a titanium dioxide (TiO ₂ ) precursor forming a second metal oxide layer.

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The third step includes: a first process of injecting ultrapure water and a substrate into a reactor through which a current flows between the stirring rod and the inner wall; A second process of forming a first metal oxide layer formed of tin oxide (SnO) having a rutile crystal structure on the surface of the substrate by introducing and stirring HCl and the tin oxide (SnO) precursor into the reactor; HCl and the titanium dioxide (TiO ₂ ) precursor are added to the reactor and stirred to form a second metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the first metal oxide layer. The third process; A fourth process of dehydrating in the reactor and then washing the substrate on which the first metal oxide layer and the second metal oxide layer are formed using ultrapure water; And a fifth process of recovering pigment particles by drying the substrate on which the first metal oxide layer and the second metal oxide layer are formed.

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The third step further includes a sixth step of further forming a protective layer by coating sodium silicate (Na ₂ SiO ₃ ) on the surface of the pigment particles after the fifth step.

A seventh process of injecting ultrapure water and pigment particles having the protective layer formed therein into a reactor through which an electric current flows between the stirring rod and the inner wall after the sixth process; The eighth to form a third metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the protective layer by adding HCl and the titanium dioxide (TiO ₂ ) precursor to the reactor and stirring It includes more processes.

The third and eighth processes are characterized in that the thickness of formation of the second metal oxide layer and the third metal oxide layer is adjusted by adjusting a time for adding and stirring a titanium dioxide (TiO ₂ ) precursor.

The third and eighth processes are characterized by stirring for 3 to 12 at a pH of 1.6 and a temperature of 70 to 80°C.

The third and eighth processes are characterized in that the coating speed is maintained at 20 to 30 nm/hr.

According to an exemplary embodiment of the present invention, when Ti0 ₂ is coated on a substrate, the effect of easily forming Ti0 ₂ having a rutile crystal structure can be expected even at a low temperature by using SnO.

In addition, by coating using a titration method, the effect of easily adjusting the thickness of the coating layer can be expected.

In addition, compared to the conventional fluidized bed chemical vapor deposition method or uniform precipitation method, it is superior in terms of production time and production volume, and can produce pearlescent pigments of high quality while having low manufacturing costs.

In addition, according to an embodiment of the present invention, it is possible to form the coating part as a composite layer of three or more layers to form an excellent refractive index, and accordingly, anisotropy, dichroism, and birefringence of colors that change direct and indirect colors according to angles Can be indicated.

In addition, since Ti0 ₂ having a rutile crystal structure can be easily formed, the solvent resistance is excellent, and the effect of expanding the use of pearlescent pigments can be expected.

In addition, by coating two or more metal oxides, it is possible to more effectively express gloss by reducing the absorption rate of light and increasing the reflectance than before.

1 is a cross-sectional view showing pearlescent particles according to an embodiment of the present invention,
2 is a cross-sectional view showing pearlescent particles according to another embodiment of the present invention,

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only the present embodiments make the disclosure of the present invention complete, and the scope of the invention to those of ordinary skill in the art It is provided to inform you. In the drawings, the same reference numerals refer to the same elements.

First, the refractive index is first described for easy description of the present invention.

The refractive index refers to the rate at which the light flux decreases when light travels in different media. Optically, light has a wave-particle duality, which is both a particle and a wave. Light waves differ in speed in different media. That is, the speed is different when light travels in air or vacuum and when light collides with TiO ₂ and is divided into reflected light and refracted light. As such, the degree to which light passes through the interface of different media and bends is called the refractive index.

On the other hand, when the standard medium is air and the opposite medium is TiO ₂ , when the crystal structure of TiO ₂ is a rutile phase, the relative refractive index is about 2.84, which is known to have a higher refractive index than other metal oxides. This relative refractive index can be explained by Snell's law.

1 is a cross-sectional view showing pearlescent particles according to an embodiment of the present invention.

As shown in Figure 1, pearlescent particles according to an embodiment of the present invention include a substrate 100; It is coated on the surface of the substrate 100, and includes a coating portion 200 formed by coating at least two different metal oxides in stages.

The substrate 100 is made of flakes of mica. In this case, natural mica or synthetic mica may be used as the mica.

For example, the base material 100 may use a flake-shaped mica having a refractive index of about 1.5 and a thickness of 0.1 to 10 μm. At this time, the color is white, and it is preferable to use one with an even surface.

The coating part 200 may be implemented as a plurality of layers by coating different metal oxides in stages to have various refractive indices.

For example, the coating part 200 may include a first metal oxide layer 210 coated on the surface of the substrate; A second metal oxide layer 220 coated on the surface of the first metal oxide layer 210; It includes a protective layer 230 coated on the surface of the second metal oxide layer 220.

At this time, the first metal oxide layer 210 is formed of tin oxide (SnO) having a rutile (Rutile) crystal structure, and the second metal oxide layer 220 is formed of titanium dioxide (TiO ₂ ) having a rutile (Rutile) crystal structure. And, the protective layer 230 is preferably formed of sodium silicate (Na ₂ SiO ₃ ).

Therefore, since the first metal oxide layer 210 and the second metal oxide layer 220 form different high refractive oranges, the color expression is clear, and the direct and indirect colors are clear, so that a pearlescent pigment having high luminance can be implemented. have.

On the other hand, the first metal oxide layer 210 is formed of tin oxide (SnO) having a rutile crystal structure, and the tin oxide (SnO) having a rutile crystal structure has a surface of the first metal oxide layer 210 When the second metal oxide layer 220 is formed, titanium dioxide (TiO ₂ ) is induced to undergo a phase transition from an anatase crystal structure to a rutile crystal structure even at a low temperature.

Tin oxide (SnO) forming the first metal oxide layer 210 has a characteristic of reducing the absorption rate of light, and since the absorption and reflection of light has a complementary color effect, the first metal oxide layer 210 is formed of tin oxide. By forming with (SnO), it is possible to implement a pearlescent pigment having an excellent refractive index.

The second metal oxide layer 220 is formed of titanium dioxide (TiO ₂ ) having a rutile (Rutile) crystal structure, and the first metal oxide layer 210 is formed of tin oxide (SnO) having a rutile (Rutile) crystal structure. Therefore, it can be easily implemented by inducing a phase transition of titanium dioxide (TiO ₂ ) of a rutile crystal structure at a low temperature. At this time, the second metal oxide layer 220 may be formed while adjusting its thickness using a titration method. At this time, it is preferable that the thickness of the second metal oxide layer 220 is 10 to 150 nm.

Titanium dioxide (TiO ₂ ) forming the second metal oxide layer 220 has a very high refractive index, has anisotropy and non-toxic properties, and has a high hiding power and is not soluble in all solvents. In addition, titanium hydroxide is synthesized by synthesizing strong basicity such as NaOH and titanium by an appropriate method, and this titanium hydroxide is advantageous in synthesizing pearlescent pigments from matt to gloss because it has excellent color development (or color reaction). Excellent pearlescent pigments can be implemented with better quality than conventional pearlescent pigments.

The protective layer 230 is preferably formed of sodium silicate (Na ₂ SiO ₃ ), which is an inorganic adhesive.

Sodium silicate (Na ₂ SiO ₃ ) forming the protective layer 230 is an inorganic adhesive having solvent resistance, and may further enhance the solvent resistance of the second metal oxide layer 220.

On the other hand, in the present invention, a metal oxide layer may be further formed on the coating portion in order to implement a more diverse refractive index.

2 is a cross-sectional view showing pearlescent particles according to another embodiment of the present invention.

As shown in Figure 2, the pearlescent particles according to another embodiment of the present invention include a substrate 100 as in the above-described embodiment; It is coated on the surface of the substrate 100, and includes a coating portion 200 formed by coating at least two different metal oxides in stages. In addition, the coating unit 200 includes a first metal oxide layer 210 coated on the surface of the substrate 100; A second metal oxide layer 220 coated on the surface of the first metal oxide layer 210; It includes a protective layer 230 coated on the surface of the second metal oxide layer 220. However, in this embodiment, a third metal formed of titanium dioxide (TiO2) having a rutile crystal structure on the surface of the protective layer 230 is formed to have a thickness different from that of the second metal oxide layer 220 An oxide layer 240 is further formed.

In this case, the third metal oxide layer 240 is preferably formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure, like the second metal oxide layer 220.

In this case, the third metal oxide layer 240 may be formed while adjusting its thickness using a titration method similar to the second metal oxide layer 220. Therefore, it is preferable that the thickness of the third metal oxide layer 240 is also formed to be 10 to 150 nm. However, it is preferable that the thickness of the third metal oxide layer is different from that of the second metal oxide layer 220.

Thus, a difference between a direct color and an indirect color may be provided by the second metal oxide layer 220 and the third metal oxide layer 240 exposed to the outermost side, thereby enabling various colors of the pearlescent pigment to be realized.

A method for producing a pearlescent pigment constructed as described above will be described.

A method for producing a pearlescent pigment according to an embodiment of the present invention includes: a first step of preparing a substrate; A second step of preparing a precursor for forming a coating; Forming a coating on the surface of the substrate, wherein at least one of the plurality of layers forming the coating includes a third step of forming a layer made of metal oxide while adjusting its thickness using a titration method. .

At this time, in the first step, the substrate is prepared as a flake having a thickness of 0.1 to 10 μm using natural mica or synthetic mica.

In the second step, a tin oxide (SnO) precursor forming a first metal oxide layer and a titanium dioxide (TiO ₂ ) precursor forming a second metal oxide layer are separately prepared as the precursor.

Here, the tin oxide (SnO) precursor uses a tin oxide (Tin Oxide)-based material, and the titanium dioxide (TiO ₂ ) precursor uses TiOCl ₂ .

When the substrate, the tin oxide (SnO) precursor and the titanium dioxide (TiO ₂ ) precursor are prepared, a plurality of layers of coatings are sequentially coated on the substrate.

So, the third step includes a first process of introducing ultrapure water (DI Water) and a substrate into a reactor through which an electric current flows between the stirring rod and the inner wall; A second process of forming a first metal oxide layer formed of tin oxide (SnO) having a rutile crystal structure on the surface of the substrate by introducing and stirring HCl and the tin oxide (SnO) precursor into the reactor; HCl and the titanium dioxide (TiO ₂ ) precursor are added to the reactor and stirred to form a second metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the first metal oxide layer. The third process; A fourth process of dehydrating in the reactor and then washing the substrate on which the first metal oxide layer and the second metal oxide layer are formed using ultrapure water; And a fifth process of recovering pigment particles by drying the substrate on which the first metal oxide layer and the second metal oxide layer are formed.

Meanwhile, in the third process of forming the second metal oxide layer, the thickness of the second metal oxide layer may be adjusted using a titration method.

In the third process, when Ti0 ₂ is coated on the surface of the substrate, preferably the surface of the substrate on which the first metal oxide layer is formed, by using a titration method, a reaction as shown in Formula 3 below occurs.

TiOCl ₂ + 2NaOH + Mica (mica) → TiO ₂ -Mica + 2NaCl + H ₂ O… [Formula 3]

The titration method is one of the important operations in quantitative analysis, and is required to react with a certain amount of a solution of a test material in a dose analysis, and the amount of a reagent with a known concentration is obtained, and the concentration of the test material is calculated. It is a method of finding out and coating it drop by drop. Therefore, it is easy to control the thickness of the coating layer productively by depositing titanium dioxide (TiO ₂ ) generated by neutralizing titanium chloride (TiOCl ₂ ) with ammonia or sodium hydroxide (2NaOH) and coating it on mica. .

And, after the fifth process, a sixth process of further forming a protective layer on the surface of the second metal oxide layer by coating sodium silicate (Na ₂ SiO ₃ ) on the surface of the pigment particles is further performed.

Meanwhile, in order to further form a third metal oxide layer on the surface of the protective layer as in the other embodiments described above, after the sixth process, in a reactor through which a current flows between the stirring rod and the inner wall, ultrapure water (DI Water) and the protective layer are A seventh process of injecting the formed pigment particles; The eighth to form a third metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the protective layer by adding HCl and the titanium dioxide (TiO ₂ ) precursor to the reactor and stirring The process can be carried out further.

A method of manufacturing the pearlescent pigment as described above will be described through specific examples.

In the present invention, in order to control the formation thickness of the second metal oxide layer using a titration method, it is preferable to control the time for injecting and stirring the titanium dioxide (TiO ₂ ) precursor in the third process.

[Example 1]

15 ~ 30ℓ of D.I Water and 1.5 ~ 3.5kg of 0.1 ~ 10㎛ mica (Calcium Aluminum Borosilicate) are added to a 50ℓ reactor and stirred while maintaining the temperature at 70 ~ 80℃. At this time, the stirring rod uses stainless steel made of SU316L material in which Mo is synthesized, and the Moter Stirrer starts stirring.

Then, four tanks into which raw materials can be injected into the reactor are prepared.

So, a titanium dioxide (TiO ₂ ) precursor, that is, TiOCl ₂ is prepared in the first tank, and 15 to 25 ℓ of HCl, 15 to 25 kg of DI water, and tin oxide (Tin oxide) as a precursor of tin oxide (SnO) are prepared in the second tank. Oxide) 0.5 ~ 2.5kg is prepared by stirring.

In addition, NaOH is prepared for pH control in the third tank, and sodium silicate (Na ₂ SiO ₃ ) aqueous solution for forming a protective layer is prepared in the fourth tank.

When the raw materials are prepared in this way, the raw materials prepared in the first to fourth tanks are introduced into the reactor in a predetermined order to perform coating.

At this time, the feed rates of the raw materials introduced into the reactor from the first to fourth tanks are all maintained at a rate of 5±3 ml/min.

Then, after adjusting the pH inside the reactor to 1.6, coating is started.

First, raw materials are supplied from the second tank and the third tank to the reactor, and the mixture is maintained for 30 minutes while stirring at 35±5 RPM. Then, tin oxide (Tin Oxide), which is a tin oxide (SnO) precursor, reacts inside the reactor to form a first metal oxide layer on the surface of the substrate.

Then, raw materials are supplied from the first tank and the third tank to the reactor, and the mixture is stirred at 45±5 RPM and maintained for 3 to 4 hours. Then, inside the reactor, a second metal oxide layer is formed on the surface of the first metal oxide layer at a rate of 20 to 30 nm/hr.

Subsequently, the substrate on which the first metal oxide layer and the second metal oxide layer are formed is taken out from the reactor, dehydrated, and washed 4 times with D.I Water.

Then, the substrate on which the first metal oxide layer and the second metal oxide layer are formed is again added to the reactor, and the mixture is stirred at 45±5 RPM and maintained for 1 hour. Then, a protective layer is formed on the surface of the second metal oxide layer.

Subsequently, the substrate on which the protective layer is formed is taken out from the reactor, dehydrated, and washed 4 times with D.I Water.

After washing, it is dried at 350°C for 24 hours.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having a rutile crystal structure having a thickness of 40 to 60 nm forms the second metal layer was recovered. The recovered pearlescent pigment had a very high refractive index white.

[Example 2]

Example 2 except that the holding time was maintained for 5 to 7 hours in the process of supplying raw materials to the reactor from the first tank and the third tank, which are the processes of forming the second metal oxide layer, and stirring at 45±5 RPM. Was prepared a pearlescent pigment under the same conditions as in Example 1.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having a rutile crystal structure having a thickness of 60 to 80 nm forms the second metal layer was recovered. The recovered pearlescent pigment had a very high refractive index yellow.

[Example 3]

Example 3, except that the holding time was maintained for 8 to 9 hours in the process of supplying raw materials to the reactor from the first tank and the third tank, which are the processes of forming the second metal oxide layer, and stirring at 45±5 RPM. Was prepared a pearlescent pigment under the same conditions as in Example 1.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having a rutile crystal structure of 80 to 100 nm thick forms the second metal layer was recovered. The recovered pearlescent pigment exhibited a red color having a very high refractive index.

[Example 4]

Example 4 except that the holding time was maintained for 10 to 11 hours in the process of supplying raw materials to the reactor from the first tank and the third tank, which are the processes of forming the second metal oxide layer, and stirring at 45±5 RPM. Was prepared a pearlescent pigment under the same conditions as in Example 1.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having a rutile crystal structure having a thickness of 100 to 140 nm forms the second metal layer was recovered. The recovered pearlescent pigment had a very high refractive index blue.

[Example 5]

Example 5, except that the holding time was maintained for 11 to 12 hours in the process of supplying raw materials to the reactor from the first tank and the third tank, which are the processes of forming the second metal oxide layer, and stirring at 45±5 RPM. Was prepared a pearlescent pigment under the same conditions as in Example 1.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having a rutile crystal structure having a thickness of 140 to 160 nm formed the second metal layer was recovered. The recovered pearlescent pigment had a very high refractive index green.

[Comparative Example]

Comparative Example is an Example except that the process of supplying raw materials from the second tank and the third tank to the reactor, which is the process of forming the first metal oxide layer, and maintaining the process for 30 minutes while stirring at 35±5 RPM is not performed. A pearlescent pigment was prepared under the same conditions as in 1.

Thus, a pearlescent pigment in which titanium dioxide (TiO ₂ ) having an anatase crystal structure having a thickness of 40 to 60 nm forms the second metal layer was recovered. The color of the recovered pearlescent pigment was white, similar to that of the first embodiment.

As can be seen in Examples 1 to 5 above, it was confirmed that the thickness of the second metal oxide layer can be adjusted to a desired level by adjusting the coating time of the second metal oxide layer using a titration method. , It was confirmed that the color implemented according to the thickness of the second metal oxide layer can be adjusted.

In addition, as can be seen from the comparison between Examples and Comparative Examples, when the first metal oxide layer is formed before the second metal oxide layer is formed, and SnO is used together to form the second metal oxide layer, 70 ~ Even at a relatively low temperature of 80°C, a phase transition of titanium dioxide (TiO ₂ ) from an anatase crystal structure to a rutile crystal structure is maintained to form a second metal oxide layer having a rutile crystal structure. I could confirm that.

On the other hand, as can be seen in Examples 1 to 5, while forming the first metal oxide layer and the second metal oxide layer, NaOH is supplied to the third tank for pH adjustment while adjusting the pH inside the reactor. The hydrolysis reaction conditions for forming the first metal oxide layer or the second metal oxide layer are preferably maintained at a pH of 1.6 to 7.5 at a temperature of 70 to 80°C.

If the temperature inside the reactor is lower than 70° C., the reaction proceeds slowly and the first metal oxide layer and the second metal oxide layer having a desired thickness are not formed. In addition, if the temperature inside the reactor is higher than 80°C, a problem may occur that hydrolysis occurs in a tank containing raw materials rather than a reactor.

In addition, it is preferable that the pH inside the reactor starts at 1.6 and maintains 1.6 to 7.5 during the reaction. If the pH inside the reactor is higher than 7.5, there may be a problem that the desired gloss is not realized.

In addition, it is preferable to form a coating thickness of the first metal oxide layer or the second metal oxide layer coated on the substrate in a range of 10 to 150 nm to implement various colors of white, yellow, red, blue, and green.

In addition, the coating speed of the first metal oxide layer or the second metal oxide layer coated on the substrate is preferably maintained at 20 to 30 nm/hr. If the coating rate is slower than the suggested rate, a problem of slowing the reaction rate may occur, and if it is faster than the suggested rate, the coating may not work properly.

Although the present invention has been described with reference to the accompanying drawings and the above-described preferred embodiments, the present invention is not limited thereto, but is limited by the claims to be described later. Therefore, those of ordinary skill in the art can variously modify and modify the present invention within the scope of the technical spirit of the claims to be described later.

100: base 200: coating
210: first metal oxide layer 220: second metal oxide layer
230: protective layer 240: third metal oxide layer

Claims (15)

Substrate;
Doedoe coated on the surface of the substrate, comprising a coating portion formed by coating at least two different metal oxides step by step,
The substrate is flake mica,
The coating part,
A first metal oxide layer coated on the surface of the substrate and comprising tin oxide (SnO) having a rutile crystal structure;
A second metal oxide layer coated on the surface of the first metal oxide layer and comprising titanium dioxide (TiO ₂ ) having a rutile crystal structure;
Pearlescent pigment particles comprising a protective layer coated on the surface of the second metal oxide layer and formed of sodium silicate (Na ₂ SiO ₃ ).
delete delete In claim 1,
The coating part is formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the protective layer, and a third metal oxide layer formed with a thickness different from that of the second metal oxide layer is further formed. Pearlescent pigment particles characterized by.
The method of claim 4,
Pearlescent pigment particles, characterized in that the thickness of each of the second metal oxide layer and the third metal oxide layer is 10 ~ 150 ㎚.
As a method of producing pearlescent pigment particles in which a coating portion formed in a plurality of layers is formed on the surface of a substrate,
A first step of preparing a substrate;
A second step of preparing a precursor for forming a coating;
Forming a coating on the surface of the substrate, wherein at least one layer of the plurality of layers forming the coating includes a third step of forming a layer made of metal oxide while adjusting its thickness using a titration method, ,
In the first step, the substrate is prepared as a flake having a thickness of 0.1 to 10 μm using natural mica or synthetic mica,
In the second step, the precursor includes a tin oxide (SnO) precursor forming a first metal oxide layer and a titanium dioxide (TiO ₂ ) precursor forming a second metal oxide layer,
The third step,
A first process of injecting ultrapure water and a substrate into a reactor through which an electric current flows between the stirring rod and the inner wall;
A second process of forming a first metal oxide layer formed of tin oxide (SnO) having a rutile crystal structure on the surface of the substrate by introducing and stirring HCl and the tin oxide (SnO) precursor into the reactor;
HCl and the titanium dioxide (TiO ₂ ) precursor are added to the reactor and stirred to form a second metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the first metal oxide layer. The third process;
A fourth process of dehydrating in the reactor and then washing the substrate on which the first metal oxide layer and the second metal oxide layer are formed using ultrapure water;
A method for producing pearlescent pigment particles comprising a fifth step of recovering the pigment particles by drying the substrate on which the first metal oxide layer and the second metal oxide layer are formed.
delete delete delete delete The method of claim 6,
The third step,
The method for producing pearlescent pigment particles further comprising a sixth process of forming a protective layer by coating sodium silicate (Na ₂ SiO ₃ ) on the surface of the pigment particles after the fifth process.
The method of claim 11,
After the sixth process
A seventh process of injecting ultrapure water and pigment particles having the protective layer formed therein into a reactor through which an electric current flows between the stirring rod and the inner wall;
The eighth to form a third metal oxide layer formed of titanium dioxide (TiO ₂ ) having a rutile crystal structure on the surface of the protective layer by adding HCl and the titanium dioxide (TiO ₂ ) precursor to the reactor and stirring A method for producing pearlescent pigment particles further comprising a process.
The method of claim 12,
The third and eighth processes are pearlescent pigment particles, characterized in that the formation thickness of the second metal oxide layer and the third metal oxide layer is controlled by adding a titanium dioxide (TiO ₂ ) precursor and adjusting the stirring time. Method of manufacturing.
The method of claim 13,
The third and eighth processes are a method for producing pearlescent pigment particles, characterized in that stirring for 3 to 12 at a pH of 1.6 and a temperature of 70 to 80°C.
The method of claim 14,
In the third and eighth processes, the method for producing pearlescent pigment particles, characterized in that the coating speed is maintained at 20 to 30 nm/hr.

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