Gold pigment with high color strength

Abstract

A gold pigment is disclosed. The gold pigment according to the present disclosure includes a substrate; a first coating layer formed on a surface of the substrate and including a metal oxide having a refractive index of more than 1.8; a second coating layer formed on the first coating layer and including an oxide containing manganese; a third coating layer formed on the second coating layer and including a colorless metal oxide having a refractive index of 1.8 or less; a fourth coating layer formed on the third coating layer and including a metal oxide having a refractive index of more than 1.8; and a fifth coating layer formed on the fourth coating layer and including Fe.sub.2O.sub.3.

Claims

1. A gold pigment comprising: a substrate; a first coating layer formed on the surface of the substrate and comprising a metal oxide having a refractive index of more than 1.8; a second coating layer formed on the first coating layer and comprising an oxide containing manganese, wherein the oxide containing manganese is formed from MnCl.sub.2 under a condition of pH 6 to 8; a third coating layer formed on the second coating layer and comprising a colorless metal oxide having a refractive index of 1.8 or less; a fourth coating layer formed on the third coating layer and comprising a metal oxide having a refractive index of more than 1.8; and a fifth coating layer formed on the fourth coating layer and containing Fe.sub.2O.sub.3.

2. The gold pigment according to claim 1, wherein the first coating layer is formed only of TiO.sub.2.

3. The gold pigment according to claim 1, wherein the first coating layer and the fourth coating layer comprise a rutile or anatase TiO.sub.2 structure.

4. The gold pigment according to claim 1, wherein the thickness of the second coating layer comprising the oxide containing manganese ranges from 0.1 nm to 20 nm.

5. The gold pigment according to claim 1, wherein the third coating layer comprises at least one selected from the group consisting of SiO.sub.2, MgO.SiO.sub.2, and AlO.sub.3.

6. The gold pigment according to claim 1, wherein the fourth coating layer comprises TiO.sub.2.

7. A gold pigment comprising a plurality of layered structure having a coating layer containing TiO.sub.2 and a coating layer containing Fe.sub.2O.sub.3, on a substrate, wherein the coating layer containing Fe.sub.2O.sub.3 is located on an upper side of the coating layer containing TiO.sub.2, a coating layer containing an oxide containing manganese is formed between the coating layer containing Fe.sub.2O.sub.3 and the coating layer containing TiO.sub.2, and the oxide containing manganese is from MnCl.sub.2 under a condition of pH 6 to 8.

8. The gold pigment according to claim 1, wherein the thickness of the first coating layer ranges from 100 nm to 200 nm.

9. The gold pigment according to claim 1, wherein the e thickness of the second coating layer is the smallest among the thicknesses of the first coating layer to the fifth coating layer.

10. The gold pigment according to claim 1, wherein the thickness of the third coating layer ranges from 10 nm to 200 nm.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 schematically shows a conventional gold pigment.

(2) FIG. 2 schematically shows another conventional gold pigment.

(3) FIG. 3 schematically shows a gold pigment according to one embodiment of the present disclosure.

(4) FIG. 4 show optical microscope (50 magnification) photographs of gold pigments according to Comparative Example 1 and Example 1.

BEST MODE

(5) Advantages and features of the present disclosure, and methods of achieving the same will be apparent with reference to the embodiments described below in detail. However, the present disclosure is not limited to the embodiments described below, but may be embodied in various forms. It is to be understood that the embodiments of the present disclosure are for the completeness of the disclosure and are provided to fully disclose the scope thereof to a person having ordinary skill in the art to which the present disclosure belongs. The present disclosure is only defined by the scope of the accompanying claims.

(6) Hereinafter, a gold pigment according to the present disclosure will be described in detail with reference to the accompanying drawings.

(7) FIG. 3 schematically shows a gold pigment according to one embodiment of the present disclosure.

(8) Referring to FIG. 3, a gold pigment according to an embodiment of the present disclosure includes a substrate 100, a first coating layer 310, a second coating layer 320, a third coating layer 330, a fourth coating layer 340, and a fifth coating layer 350.

(9) The coating layers 310 to 350 are each formed to a thickness of about 0.5 m or less and may be formed at 60 C. to 90 C., respectively.

(10) The first to fifth coating layers 310 to 350 may be formed only once in this order, and may be formed repeatedly in this order more than once, if necessary. In addition, an additional coating layer may be further formed between each coating layer, and a protective coating layer may be further formed on the fifth coating layer 350, that is, the uppermost coating layer, for the purpose of improving weatherability or the like.

(11) The substrate 300 may be formed of natural mica, synthetic mica, glass flake, alumina flake, or the like. The substrate 300 may generally be a platelet substrate having a particle size of about 5 to 600 m, but is not limited thereto and various known substrates can be used.

(12) The first coating layer 310 is formed on the surface of the substrate 300 and includes a metal oxide having a refractive index of more than 1.8. The first coating layer 210 is a powder having a gold color under a black background and serves to determine a basic color.

(13) At this time, the first coating layer may be formed to have a thickness of about 100 to 200 nm with only TiO.sub.2. TiO.sub.2 may have a rutile or an anatase structure, and more preferably a rutile structure. In the case of rutile structure TiO.sub.2, there is an advantage that the gloss and the stability are more excellent. Such rutile structure TiO.sub.2 coating layer may be formed by pretreating the substrate surface with a tin compound such as SnCl.sub.4 and then coating TiO.sub.2 with TiCl.sub.4 or the like.

(14) When the first coating layer 310 and the fourth coating layer 340 described later are formed of TiO.sub.2, the first coating layer 310 and the fourth coating layer 340 may be formed from TiCl.sub.4 under strong acidic conditions of pH 3 or less.

(15) The second coating layer 320 is formed on the first coating layer 310 and includes an oxide containing manganese such as MnO. Such manganese-containing oxides may include MnO and MnO.sub.2, and they are blackish brown, and any one of them may be used, or both of them may be used in combination.

(16) The gold color realized by a white TiO.sub.2 coating layer and a red Fe.sub.2O.sub.3 coating layer is somewhat reddish. However, as in the present disclosure, a Mn-containing oxide coating layer (such as 320 in FIG. 3) such as MnO between the white TiO.sub.2 coating layer (such as 310 in FIG. 3) and the red Fe.sub.2O.sub.3 (such as 350 in FIG. 3) is included, the gold color can be more accurately represented by removing some of the red tone from the conventional reddish gold color.

(17) The second coating layer 320 comprising a manganese-containing oxide may be formed from MnCl.sub.2 under neutral conditions of pH 6 to 8.

(18) The third coating layer 330 is formed on the second coating layer 320 to a thickness of about 10 to 200 nm and includes a colorless metal oxide having a refractive index of 1.8 or less. The third coating layer 230 is a low refractive index layer which is positioned between a high refractive index layer (such as 310 in FIG. 3) and a high refractive index layer (such as 340 and 350 in FIG. 3) to allow for the gold pigment according to the present disclosure to act as an interference pigment.

(19) The colorless metal oxide having a refractive index of 1.8 or less may include at least one of SiO.sub.2, MgO.SiO.sub.2, and Al.sub.2O.sub.3.

(20) The fourth coating layer 340 is formed on the surface of the third coating layer 330 and includes a metal oxide having a refractive index of more than 1.8. The fourth coating layer 340 may be formed of a white metal oxide, for example, TiO.sub.2 coating layer.

(21) The fifth coating layer 350 is formed on the fourth coating layer 340 and includes Fe.sub.2O.sub.3.

(22) Such Fe.sub.2O.sub.3 corresponds to a high refractive red metal oxide having a refractive index exceeding 1.8.

(23) The fifth coating layer may be formed from an iron-containing compound such as FeCl.sub.3 or the like under an acidic condition of pH 2 to 4.

(24) A desired effect can be achieved when the thickness of the second coating layer 320 including a manganese oxide is a specific thickness among the first to fifth coating layers 310 to 350. If the thickness of the manganese oxide is too thin, the effect of reducing the red tone may be insufficient, and if it is too thick, the gloss or the like may be deteriorated. More preferably, the content of the second coating layer may be 0.1 to 10 parts by weight based on 100 parts by weight of the substrate, wherein the thickness of the second coating layer may be 0.1 to 20 nm.

(25) The gold pigment of the present disclosure does not have to include all of the five coating layers shown in FIG. 2, and all of the conditions including three or more coating layers as described below are included in the scope of the present disclosure.

(26) That is, the gold pigment of the present disclosure has a plurality of layered structure in which a coating layer containing TiO.sub.2 and a coating layer containing Fe.sub.2O.sub.3 are formed on the substrate, but any of those structures in which the coating layer containing Fe.sub.2O.sub.3 is located on an upper side of the coating layer containing TiO.sub.2, and a coating layer containing a manganese-containing oxide is formed between a coating layer containing Fe.sub.2O.sub.3 and a coating layer containing TiO.sub.2 can be applied to the present disclosure.

EXAMPLES

(27) Hereinafter, the present disclosure will be described in more detail with reference to preferred embodiments thereof. It is to be understood, however, that the embodiments are intended to be illustrative and are not to be construed as limiting the disclosure in any way.

(28) The contents not described herein can be sufficiently technically inferred to those having ordinary skill in the art, and a description thereof will be omitted.

(29) 1. Preparation of Gold Pigments

Example 1

(30) 100 g of synthetic mica flakes having a particle size of 5 to 560 m were introduced into 1 L demineralized water and stirred to form a slurry. Then, after the slurry was heated to 75 C., the pH of the slurry was adjusted to 1.7 by adding an HCl solution (Formation of substrate slurry).

(31) Then, 30 g of SnCl.sub.4 solution (SnCl.sub.4 content 11 wt. %) was weighed and titrated in the slurry at a constant rate over 1 hour while the pH was kept constant at 1.7 with 30% NaOH diluent.

(32) Then, 300 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant at 1.7 with 30% NaOH diluent. After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 7.0 with 20% NaOH diluent (Formation of first coating layer).

(33) Then, 100 g of MnCl.sub.2 solution (MnCl.sub.2 content 3 wt. %) was weighed and titrated in the slurry over 2 hours while the pH was kept constant at 6.0 to 8.0 with 30% NaOH diluent. After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 7.5 with 20% NaOH diluent (Formation of second coating layer).

(34) Then, 900 g of MgO.SiO.sub.2 solution (MgO.SiO.sub.2 content 3.5 wt. %) was weighed and titrated in the slurry over 4 hours while the pH was kept constant at 7.5 with HCl solution. Then, an HCl solution was added to adjust the pH of the slurry to 1.7, and the mixture was further refluxed with stirring for 15 minutes (Formation of third coating layer).

(35) Then, 30 g of SnCl.sub.4 solution (SnCl.sub.4 content 11 wt. %) was weighed and titrated in the slurry at a constant rate over 1 hour while the pH was kept constant at 1.7 with 30% NaOH diluent.

(36) Then, 250 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant with 30% NaOH diluent (Formation of fourth coating layer).

(37) After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 3.2 with 20% NaOH diluent.

(38) Then, 150 g of FeCl.sub.3 solution (FeCl.sub.3 content 20 wt. %) was weighed and titrated in the slurry over 2 hours while the pH was kept constant at 3.2 with 30% NaOH diluent (Formation of fifth coating layer).

(39) After refluxing, the final slurry was filtered off and dewatered, washed twice with demineralized water, and then dried at 120 C. for 10 hours to give an intermediate product in powder form.

(40) Then, the obtained intermediate product was calcined at 800 C. for 12 minutes to obtain a gold pigment powder.

Example 2

(41) 100 g of synthetic mica flakes having a particle size of 5 to 560 m were introduced into 1 L demineralized water and stirred to form a slurry. Then, after the slurry was heated to 75 C., the pH of the slurry was adjusted to 1.7 by adding an HCl solution (Formation of substrate slurry).

(42) Then, 300 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant at 2.4 with 30% NaOH diluent. After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 7.0 with 20% NaOH diluent (Formation of first coating layer).

(43) Then, 100 g of MnCl.sub.2 solution (MnCl.sub.2 content 3 wt. %) was weighed and titrated in the slurry over 2 hours while the pH was kept constant at 6.0 to 8.0 with 30% NaOH diluent. After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 7.5 with 20% NaOH diluent (Formation of second coating layer).

(44) Then, 900 g of MgO.SiO.sub.2 solution (MgO.SiO.sub.2 content 3.5 wt. %) was weighed and titrated in the slurry over 4 hours while the pH was kept constant at 7.5 with HCl solution. Then, an HCl solution was added to adjust the pH of the slurry to 2.4, and the mixture was further refluxed with stirring for 15 minutes (Formation of third coating layer).

(45) Then, 250 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant with 30% NaOH diluent (Formation of fourth coating layer).

(46) After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 3.2 with 20% NaOH diluent.

(47) Then, 150 g of FeCl.sub.3 solution (FeCl.sub.3 content 20 wt. %) was weighed and titrated in the slurry over 2 hours while the pH was kept constant at 3.2 with 30% NaOH diluent (Formation of fifth coating layer).

(48) After refluxing, the final slurry was filtered off and dewatered, washed twice with demineralized water, and then dried at 120 C. for 10 hours to give an intermediate product in powder form.

(49) Then, the obtained intermediate product was calcined at 800 C. for 12 minutes to obtain a gold pigment powder.

(50) In the gold pigment powder prepared according to Example 1, the TiO.sub.2 structure of the first coating layer and the fourth coating layer showed a rutile structure, whereas in the gold pigment powder prepared according to Example 2, the TiO.sub.2 structure of the first coating layer and the fourth coating layer exhibited an anatase structure.

Comparative Example 1

(51) 100 g of mica with a particle size of 10 to 60 m was heated to 75 C. in 2 L demineralized water. When the temperature was reached, a solution of 130.5 g of FeCl.sub.36H.sub.2O, 46.5 g of TiCl.sub.4 and 11.6 g of AlCl.sub.36H.sub.2O in 84.3 g of demineralized water was slowly added dropwise with vigorous stirring. The pH was maintained at 2.6 with 32% aqueous solution of sodium hydroxide. After addition of the solution, the mixture was further stirred for approximately 15 minutes. Then, the pH was raised to 7.5 with a 32% aqueous solution of sodium hydroxide, and 431 g of a sodium water glass solution (13.5% of SiO.sub.2) was slowly added dropwise at this pH. Then, the mixture was lowered to pH 2.0 with 10% hydrochloric acid, and then the mixture was further stirred for 15 minutes and 396 g of a TiCl.sub.4 solution (370 g/L of TiCl.sub.4) was added dropwise. The pH was maintained at 2.6 with 32% aqueous solution of sodium hydroxide. After addition of the solution, the mixture was further stirred for approximately 15 minutes. The pH was then raised to 5.0 with 32% solution of sodium hydroxide, and the mixture was stirred for additional 15 minutes.

(52) After refluxing, the final slurry was filtered off and dewatered, washed twice with demineralized water, and then dried at 120 C. for 10 hours to give an intermediate product in powder form.

(53) Then, the obtained intermediate product was calcined at 800 C. for 12 minutes to obtain a gold pigment powder.

(54) The gold pigment powder prepared according to Comparative Example 1 had the structure shown in FIG. 1.

Comparative Example 2

(55) 100 g of synthetic mica flakes having a particle size of 5 to 560 m were introduced into 1 L demineralized water and stirred to form a slurry. Then, after the slurry was heated to 75 C., the pH of the slurry was adjusted to 1.7 by adding an HCl solution (Formation of substrate slurry).

(56) Then, 30 g of SnCl.sub.4 solution (SnCl.sub.4 content 11 wt. %) was weighed and titrated in the slurry at a constant rate over 1 hour while the pH was kept constant at 1.7 with 30% NaOH diluent.

(57) Then, 300 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant at 1.7 with 30% NaOH diluent. After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 7.5 with 20% NaOH diluent (Formation of first coating layer).

(58) Then, 900 g of MgO.SiO.sub.2 solution (MgO.SiO.sub.2 content 3.5 wt. %) was weighed and titrated in the slurry over 4 hours while the pH was kept constant at 7.5 with HCl solution. Then, an HCl solution was added to adjust the pH of the slurry to 1.7, and the mixture was further refluxed with stirring for 15 minutes (Formation of second coating layer).

(59) Then, 30 g of SnCl.sub.4 solution (SnCl.sub.4 content 11 wt. %) was weighed and titrated in the slurry at a constant rate over 1 hour while the pH was kept constant at 1.7 with 30% NaOH diluent.

(60) Then, 250 g of TiCl.sub.4 solution (TiCl.sub.4 content 33 wt. %) was weighed and titrated in the slurry over 8 hours while the pH was kept constant with 30% NaOH diluent (Formation of third coating layer).

(61) After titration, the mixture was refluxed for 10 minutes, and the pH was adjusted to 3.2 with 20% NaOH diluent.

(62) Then, 150 g of FeCl.sub.3 solution (FeCl.sub.3 content 20 wt. %) was weighed and titrated in the slurry over 2 hours while the pH was kept constant at 3.2 with 30% NaOH diluent (Formation of fourth coating layer).

(63) After refluxing, the final slurry was filtered off and dewatered, washed twice with demineralized water, and then dried at 120 C. for 10 hours to give an intermediate product in powder form.

(64) Then, the obtained intermediate product was calcined at 800 C. for 12 minutes to obtain a gold pigment powder.

(65) The gold pigment powder prepared according to Comparative Example 2 had the structure shown in FIG. 2.

(66) 2. Evaluation of Physical Properties

(67) Evaluation of Saturation

(68) Table 1 shows color difference values (a*, b*) of the gold pigments according to Example 1 and Comparative Examples 1 and 2. The color difference value was determined with Konika Minolta Chroma meter CR-400 D65, where L* indicates glossiness, a* is the red coordinate, b* is the yellow coordinate, and L*. a* and b* are color difference values between the Comparative Example and Example 1 having the same substrates and colors.

(69) In addition, FIG. 4 shows optical microscope (50 magnification) photographs of gold pigments according to Comparative Example 1 and Example 1.

(70) TABLE-US-00001 TABLE 1 L* a* b* L* a* b* C. Ex. 1 74.87 3.21 55.67 C. Ex. 2 71.33 0.14 49.74 3.54 3.08 5.92 Ex. 1 78.24 0.74 57.01 +3.37 3.95 +1.35

(71) Referring to Table 1 and FIG. 4, it can be seen that the color difference values (L*, a*, b*) were changed after the MnO coating layer was used, as a result of comparing Comparative Examples with Example 1.

(72) More specifically, in the case of Example 1, Red color decreased and Yellow color increased as compared with Comparative Examples 1 and 2, and thereby the red tone decreased and the gloss was rather increased

(73) [Applications]

(74) The following is a description of application examples in which the gold pigment obtained in Example 1 is used in paints, plastics, inks and cosmetics.

(75) (1) Paints

(76) This is an example of paints for use in automotive surface coatings.

(77) {Base Coating Composition}

(78) [Polyester Resin]

(79) Hayikyu base for toning transparent (BC-1000) (available from NOROO Painting & Coating Co., Ltd.)

(80) Hayikyu LV thinner (DR-950WS) (available from NOROO Painting & Coating Co., Ltd.)

(81) 4 parts by weight of the gold pigment obtained in Example 1 and 96 parts by weight of the polyester resin composition were mixed, and 100 parts by weight of a diluent for the polyester resin was added to the mixture and the viscosity was reduced to a concentration suitable for spray coating (applied using Ford Cup #4 for 14 to 16 seconds (25 C.), which was then applied by spray coating to form an undercoat layer. An uncolored surface clear paint of the following composition was applied over the undercoat layer.

(82) {Surface Clear Paint}

(83) Hayikyu UltraClear (available from NOROO Paintings & Coating Co., Ltd.)

(84) Hayikyu UltraClear hardener (CCH-100) (available from NOROO Painting & Coating Co., Ltd.)

(85) After surface coating, the paint was exposed to air at 40 C. for 30 minutes and heated for curing at 130 C. for 30 minutes.

(86) (2) Plastics

(87) The following are an example of pigment compositions used to color plastics.

(88) Polyethylene resin (pellet): 70 parts by weight

(89) The gold pigment obtained in Example 1: 1 part by weight

(90) Zinc stearate 0.2 part by weight

(91) Liquid paraffin: 0.1 part by weight

(92) The pellets containing the composition were dry blended and extruded.

(93) (3) Cosmetics

(94) The following are compositions for lip-color cosmetics.

(95) Hydrogenated Castor Oil37 parts by weight

(96) Octyldodecanol10 parts by weight

(97) Diisostearyl Malate20 parts by weight

(98) Ceresin5 parts by weight

(99) Euphorbia Cerifera (Candelilla) Wax5 parts by weight

(100) Dipentaerythrityl Hexahydroxystearate/Hexastearate/Hexarosinate18.5 parts by weight

(101) Copernicia Cerifera (Carnauba) Wax3 parts by weight

(102) Isopropyl Lanolate1 part by weight

(103) VP/Hexadecene Copolymer1 part by weight

(104) The gold pigment obtained in Example 1: Proper amount

(105) Antioxidants, preservatives and fragrances: Small amount

(106) Lipstick was formed from the composition.

(107) While the present disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but, on the contrary, the present disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.