Composite reflective flake based pigments

• US 20030207113A1
• Filed: 03/27/2003
• Published: 11/06/2003
• Est. Priority Date: 07/27/2000
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Flex Products Incorporated (Sicpa Holding SA)
• Inventors: Matteucci, John S., Matteucci, Mary E., Mayer, Thomas, Phillips, Roger W., Coulter, Kent E.
• Granted Patent: US 6,699,313 B2
• Time in Patent Office: Days
• US Class Current: 428/403
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/84 one phase coated with the other
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0024 comprising a stack of coating layers with alternating high and low refractive indices, wherein the first coating layer on the core surface has the high refractive index
• CPC Class Codes: C09C 1/0051 comprising a stack of coating layers with alternating low and high refractive indices, wherein the first coating layer on the core surface has the low refractive index
• CPC Class Codes: C09C 1/0078 Pigments consisting of flaky, non-metallic substrates, characterised by a surface-region containing free metal
• CPC Class Codes: C09C 2200/1008 comprising at least one metal layer adjacent to the core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1012 with a protective coating on the metal layer
• CPC Class Codes: C09C 2200/1025 comprising at least one metal layer adjacent to core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1029 with a protective coating on the metallic layer
• CPC Class Codes: C09C 2200/1041 comprising at least one metal layer adjacent to core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1045 with a protective coating on the metallic layer
• CPC Class Codes: C09C 2200/1091 comprising at least one metal layer adjacent to the core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1095 comprising a protective coating on the metal layer
• CPC Class Codes: C09C 2200/301 Thickness of the core
• CPC Class Codes: C09C 2200/304 Thickness of intermediate layers adjacent to the core, e.g. metallic layers, protective layers, rutilisation enhancing layers or reflective layers
• CPC Class Codes: C09D 5/36 Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

A flake-based pigment is provided having improved specular reflectance characteristics in the visible wavelength range. The flake-based pigment has a plurality of composite reflective flakes each formed of a support layer and a reflector layer on one or both opposing sides of the support layer. This flake structure exhibits a uniaxial compressive strength much greater than a corresponding uniaxial tensile strength. The structure of the flakes provides the benefits of rigidity and brittle fracture during manufacture and application processes, which ultimately provides favorable planar and specular reflectance characteristics to the pigment in the visible wavelength range. A variety of outer coating layers can be formed around the composite reflective flakes, such as various dielectric and/or absorber layers, to produce desired optical characteristics in the pigment.

Claims

1. A composite reflective flake providing high reflectance during use as a pigment, the flake comprising:

a central support layer having a first major surface, an opposing second major surface, and at least one side surface, the support layer having a thickness in a range of about 50 nm to about 1000 nm; and

a reflector layer on each of the first and second major surfaces of the support layer but not on the at least one side surface, each reflector layer having a thickness in a range of about 10 nm to about 150 nm.

2. The flake of claim 1, wherein the support layer is composed of an inorganic material and the reflector layer includes a metal.

3. The flake of claim 1, wherein the support layer comprises a dielectric material selected from the group consisting of metal fluorides, metal oxides, metal sulfides, metal nitrides, metal carbides, and combinations thereof.

4. The flake of claim 1, wherein the support layer comprises a dielectric material selected from the group consisting of magnesium fluoride, silicon monoxide, silicon dioxide, aluminum oxide, titanium dioxide, zinc sulfide, tungsten oxide, aluminum nitride, boron nitride, boron carbide, tungsten carbide, titanium carbide, titanium nitride, silicon nitride, glass flakes, diamond-like-carbon, and combinations thereof.

5. The flake of claim 1, wherein the support layer comprises a material selected from the group consisting of a natural platelet mineral, a synthetic platelet material, and combinations thereof.

6. The flake of claim 1, wherein the support layer comprises a preflake material selected from the group consisting of mica peroskovite, micaeous iron oxide, coated mica, boron nitride, boron carbide, carbon, graphite, glass, alumina, silicon dioxide, and combinations thereof.

7. The flake of claim 1, wherein the support layer comprises a material selected from the group consisting of carbon, graphite, silicon, metal silicides, semiconductive compounds formed from group III, IV, or V elements, metals having a body centered cubic crystal structure, cermet compositions or compounds, semiconductive glasses, and combinations thereof.

8. The flake of claim 1, wherein the reflector layer comprises a material selected from the group consisting of aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, tin, niobium, chromium, titanium, and combinations or alloys thereof.

9. The flake of claim 1, further comprising an optical coating on at least one reflector layer.

10. The flake of claim 9, wherein the optical coating includes one or more layers composed of a material selected from the group consisting of a dielectric material, an absorber material, and combinations thereof.

11. The flake of claim 1, further comprising a protective layer on at least one reflector layer.

12. The flake of claim 11, wherein the protective layer is composed of a dielectric material selected from the group consisting of metal fluorides, metal oxides, metal sulfides, metal nitrides, metal carbides, and combinations thereof.

13. The flake of claim 11, wherein the protective layer is composed of an organic material having vapor and gas barrier properties.

14. The flake of claim 13, wherein the organic material comprises polymers of xylylene.

15. The flake of claim 11, further comprising an optical coating on at least one protective layer.

16. A composite reflective flake providing high reflectance during use as a pigment, the flake comprising:

a central support layer having a top surface, a bottom surface, and at least one side surface, the support layer composed of a substantially brittle material having a first thickness; and

a reflector layer having a second thickness on each of the top and bottom surfaces but not on the at least one side surface, at least one reflector layer composed of a substantially ductile material;

wherein the ratio of the first thickness and the second thickness is sufficient to induce a substantially brittle failure of the ductile reflector layer.

17. The flake of claim 16, wherein the first thickness has a range of about 50 nm to about 150 nm.

18. The flake of claim 16, wherein the second thickness has a range of about 10 nm to about 150 nm.

19. A composite reflective flake providing high reflectance during use as a pigment, the flake comprising:

a central support layer having substantially smooth and parallel first and second major surfaces; and

a reflector layer on each of the first and second major surfaces of the support layer, at least one of the reflector layers being a continuous thin film which substantially replicates the underlying first or second major surface;

wherein the composite reflective flake has a reflectivity of greater than about 80 percent.

20. The flake of claim 19, wherein the support layer has a thickness in a range of about 50 nm to about 150 nm.

21. The flake of claim 19, wherein each reflector layer has a thickness in a range of about 10 nm to about 150 nm.

22. A highly reflective flake-based pigment, comprising:

a plurality of composite reflective flakes with substantial rigidity, each of the composite reflective flakes including a central support layer having a first major surface, an opposing second major surface, and at least one side surface, and a reflector layer on each of the first and second major surfaces of the support layer but not on the at least one side surface;

a first dielectric coating substantially surrounding each of the composite reflective flakes; and

a first absorber coating substantially surrounding the first dielectric coating.

23. The pigment of claim 22, wherein the support layer comprises a dielectric material selected from the group consisting of magnesium fluoride, silicon monoxide, silicon dioxide, aluminum oxide, titanium dioxide, zinc sulfide, tungsten oxide, aluminum nitride, boron nitride, boron carbide, tungsten carbide, titanium carbide, titanium nitride, silicon nitride, glass flakes, diamond-like-carbon, and combinations thereof.

24. The pigment of claim 22, wherein the support layer comprises a preflake material selected from the group consisting of mica peroskovite, micaeous iron oxide, coated mica, boron nitride, boron carbide, carbon, graphite, glass, alumina, silicon dioxide, and combinations thereof.

25. The pigment of claim 22, wherein the support layer comprises a material selected from the group consisting of carbon, graphite, silicon, metal suicides, semiconductive compounds formed from group III, IV, or V elements, metals having a body centered cubic crystal structure, cermet compositions or compounds, semiconductive glasses, and combinations thereof.

26. The pigment of claim 22, wherein the reflector layer comprises a material selected from the group consisting of aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, tin, niobium, chromium, titanium, and combinations or alloys thereof.

27. The pigment of claim 22, wherein the first dielectric coating has an index of refraction of about 1.65 or less.

28. The pigment of claim 27, wherein the first dielectric coating comprises a material selected from the group consisting of silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, sodium aluminum fluorides, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, lithium fluoride, and combinations thereof.

29. The pigment of claim 27, wherein the first dielectric coating comprises a material selected from the group consisting of acrylates, perfluoroalkenes, polytetrafluoroethylene, fluorinated ethylene propylene, and combinations thereof.

30. The pigment of claim 22, wherein the first dielectric coating has an index of refraction of greater than about 1.65.

31. The pigment of claim 30, wherein the first dielectric coating comprises a material selected from the group consisting of zinc sulfide, zinc oxide, zirconium oxide, titanium dioxide, carbon, indium oxide, indium-tin-oxide, tantalum pentoxide, ceric oxide, yttrium oxide, europium oxide, iron oxides, hafnium nitride, hafnium carbide, hafnium oxide, lanthanum oxide, magnesium oxide, neodymium oxide, praseodymium oxide, samarium oxide, antimony trioxide, silicon carbide, silicon nitride, silicon monoxide, selenium trioxide, tin oxide, tungsten trioxide, and combinations thereof.

32. The pigment of claim 22, wherein the first dielectric coating has a thickness in a range from about 50 nm to about 800 nm.

33. The pigment of claim 22, wherein the first absorber coating comprises a material selected from the group consisting of chromium, nickel, iron, titanium, aluminum, tungsten, molybdenum, niobium, Ni—

Cr—

Fe, and combinations or alloys thereof.

34. The pigment of claim 22, wherein the first absorber coating has a thickness in a range from about 2 nm to about 80 nm.

35. The pigment of claim 22, wherein the composite reflective flakes have a uniaxial compressive strength at least about 6 times greater than a uniaxial tensile strength thereof.

36. The pigment of claim 22, further comprising a second dielectric coating substantially surrounding the first absorber coating, and a second absorber coating substantially surrounding the second dielectric coating.

37. The pigment of claim 36, wherein the first and second dielectric coatings have an index of refraction of about 1.65 or less.

38. The pigment of claim 36, wherein the first and second dielectric coatings have an index of refraction of greater than about 1.65.

39. The pigment of claim 36, wherein the first dielectric coating has an index of refraction of about 1.65 or less, and the second dielectric coating has an index of refraction of greater than about 1.65.

40. The pigment of claim 36, wherein the first dielectric coating has an index of refraction of greater than about 1.65, and the second dielectric coating has an index of refraction of about 1.65 or less.

41. A highly reflective flake-based pigment, comprising:

a plurality of composite reflective flakes with substantial rigidity, each of the composite reflective flakes including a central support layer having a first major surface, an opposing second major surface, and at least one side surface, and a reflector layer on each of the first and second major surfaces of the support layer but not on the at least one side surface;

a first dielectric coating substantially surrounding each of the composite reflective flakes; and

a second dielectric coating substantially surrounding the first dielectric coating.

42. The pigment of claim 41, wherein the support layer comprises a dielectric material selected from the group consisting of magnesium fluoride, silicon monoxide, silicon dioxide, aluminum oxide, titanium dioxide, zinc sulfide, tungsten oxide, aluminum nitride, boron nitride, boron carbide, tungsten carbide, titanium carbide, titanium nitride, silicon nitride, glass flakes, diamond-like-carbon, and combinations thereof.

43. The pigment of claim 41, wherein the support layer comprises a preflake material selected from the group consisting of mica peroskovite, micaeous iron oxide, coated mica, boron nitride, boron carbide, carbon, graphite, glass, alumina, silicon dioxide, and combinations thereof.

44. The pigment of claim 41, wherein the support layer comprises a material selected from the group consisting of carbon, graphite, silicon, metal silicides, semiconductive compounds formed from group III, IV, or V elements, metals having a body centered cubic crystal structure, cermet compositions or compounds, semiconductive glasses, and combinations thereof.

45. The pigment of claim 41, wherein the reflector layer comprises a material selected from the group consisting of aluminum, copper, silver, gold, platinum, palladium, nickel, cobalt, tin, niobium, chromium, titanium, and combinations or alloys thereof.

46. The pigment of claim 41, wherein the first dielectric coating has an index of refraction of about 1.65 or less.

47. The pigment of claim 46, wherein the first dielectric coating comprises a material selected from the group consisting of silicon dioxide, aluminum oxide, magnesium fluoride, aluminum fluoride, cerium fluoride, lanthanum fluoride, sodium aluminum fluorides, neodymium fluoride, samarium fluoride, barium fluoride, calcium fluoride, lithium fluoride, and combinations thereof.

48. The pigment of claim 46, wherein the second dielectric coating comprises an absorbing material selected from the group consisting of an iron oxide, silicon monoxide, chromium oxide, carbon, titanium nitride, titanium sub-oxide, and combinations thereof.

49. The pigment of claim 41, wherein the first dielectric coating has an index of refraction of greater than about 1.65.

50. The pigment of claim 49, wherein the first dielectric coating comprises a material selected from the group consisting of zinc sulfide, zinc oxide, zirconium oxide, titanium dioxide, carbon, indium oxide, indium-tin-oxide, tantalum pentoxide, ceric oxide, yttrium oxide, europium oxide, iron oxides, hafnium nitride, hafnium carbide, hafnium oxide, lanthanum oxide, magnesium oxide, neodymium oxide, praseodymium oxide, samarium oxide, antimony trioxide, silicon carbide, silicon nitride, silicon monoxide, selenium trioxide, tin oxide, tungsten trioxide, and combinations thereof.

51. The pigment of claim 49, wherein the second dielectric coating comprises an absorbing material selected from the group consisting of an iron oxide, silicon monoxide, chromium oxide, carbon, titanium nitride, titanium sub-oxide, and combinations thereof.

52. The pigment of claim 46, wherein the second dielectric coating has an index of refraction of greater than about 1.65.

53. The pigment of claim 52, further comprising a third dielectric coating substantially surrounding the second dielectric coating, and a fourth dielectric coating substantially surrounding the third dielectric coating.

54. The pigment of claim 53, wherein the third dielectric coating has an index of refraction of about 1.65 or less, and the fourth dielectric coating has an index of refraction of greater than about 1.65.

55. The pigment of claim 49, wherein the second dielectric coating has an index of refraction of about 1.65 or less.

56. The pigment of claim 55, further comprising a third dielectric coating substantially surrounding the second dielectric coating, and a fourth dielectric coating substantially surrounding the third dielectric coating.

57. The pigment of claim 56, wherein the third dielectric coating has an index of refraction of greater than about 1.65, and the fourth dielectric coating has an index of refraction of about 1.65 or less.

58. A highly reflective flake-based pigment, comprising:

a plurality of composite reflective flakes with substantial rigidity, each of the composite reflective flakes comprising;

a central support layer having a first major surface, an opposing second major surface, and at least one side surface, the support layer having a thickness in a range of about 50 nm to about 1000 nm; and

at least one reflector layer on either the first or second major surface of the support layer but not on the at least one side surface, the at least one reflector layer having a thickness in a range of about 10 nm to about 150 nm; and

a film coating substantially surrounding each of the composite reflective flakes.

59. The pigment of claim 58, wherein the support layer has a thickness in a range from about 50 nm to about 150 nm.

60. The pigment of claim 58, wherein the film coating comprises a cermet material.

61. The pigment of claim 58, wherein the film coating comprises at least one layer of a magnetic material.

62. The pigment of claim 61, wherein the magnetic material comprises a cobalt-nickel alloy.

63. The pigment of claim 58, wherein the film coating comprises at least one layer of an IR reflectant material.

64. The pigment of claim 63, wherein the IR reflectant material is selected from the group consisting of oxides of indium, europium oxide, vanadium pentoxide, rhenium oxide, lanthanum boride, and combinations thereof.

65. The pigment of claim 58, wherein the film coating is an absorbing material.

66. The pigment of claim 65, wherein the absorbing material comprises an organic dye material.

67. The pigment of claim 65, wherein the absorbing material comprises an inorganic colorant material.

68. A method of fabricating a highly reflective flake-based pigment, comprising the steps of:

forming a first reflector layer on an upper surface of a web material;

forming a central support layer on the first reflector layer;

forming a second reflector layer on the central support layer to produce a core flake film; and

removing the core flake film from the web material in order to produce a plurality of composite reflective flakes.

69. The method of claim 68, further comprising the step of forming one or more coating layers around the composite reflective flakes.

70. The method of claim 69, wherein the coating layers comprise at least one dielectric coating substantially surrounding each of the composite reflective flakes, and at least one absorber coating substantially surrounding the dielectric coating.

71. The method of claim 70, wherein the dielectric coating has an index of refraction of about 1.65 or less.

72. The method of claim 70, wherein the dielectric coating has an index of refraction of greater than about 1.65.

73. The method of claim 69, wherein the coating layers comprise a first dielectric coating substantially surrounding each of the composite reflective flakes, and a second dielectric coating substantially surrounding the first dielectric coating.

74. The method of claim 73, wherein the first dielectric coating has an index of refraction of about 1.65 or less.

75. The method of claim 73, wherein the first dielectric coating has an index of refraction of greater than about 1.65.

76. The method of claim 73, wherein the second dielectric coating comprises an absorbing material.

77. The method of claim 74, wherein the second dielectric coating has an index of refraction of greater than about 1.65.

78. The method of claim 75, wherein the second dielectric coating has an index of refraction of about 1.65 or less.

79. The method of claim 69, wherein the one or more coating layers comprise a cermet material.

80. The method of claim 69, wherein the one or more coating layers comprise a magnetic material.

81. The method of claim 69, wherein the one or more coating layers comprise an IR reflectant material.

82. The method of claim 69, wherein the one or more coating layers comprise an organic dye material.

83. The method of claim 69, wherein the one or more coating layers comprise an inorganic colorant material.

84. The method of claim 69, wherein the one or more coating layers are formed by a process selected from the group consisting of vacuum vapor deposition, chemical vapor deposition, electrochemical deposition, sol-gel hydrolysis, sputtering, pyrolysis, and combinations thereof.

85. The method of claim 69, further comprising the step of dispersing the composite reflective flakes in a polymeric medium to form a colorant.

86. The method of claim 85, wherein the colorant is a paint or ink.

87. A colorant composition, comprising:

a polymeric medium; and

a plurality of composite reflective flakes dispersed in the polymeric medium and having one or more coating layers formed therearound, each of the composite reflective flakes comprising;

a central support layer having a first major surface, an opposing second major surface, and at least one side surface, the support layer having a thickness in a range of about 50 nm to about 1000 nm; and

a reflector layer on each of the first and second major surfaces of the support layer but not on the at least one side surface, each reflector layer having a thickness in a range of about 10 nm to about 150 nm.

88. The colorant composition of claim 87, wherein the one or more coating layers comprise at least one dielectric coating substantially surrounding each of the composite reflective flakes, and at least one absorber coating substantially surrounding the dielectric coating.

89. The colorant composition of claim 87, wherein the one or more coating layers comprise a first dielectric coating substantially surrounding each of the composite reflective flakes, and a second dielectric coating substantially surrounding the first dielectric coating.

90. The colorant composition of claim 87, further comprising an additive material.

91. The colorant composition of claim 87, wherein the polymeric medium is a paint or ink.