Yun Shao, Ph.D.

Kobo Products, Inc.New Jersey, USA

Application and Dispersionof

Nano Pigments for Color Cosmetics

Outline

1. Introduction of nano pigments

2. Comparison of color strength

3. Dispersion and color development of nano pigments

4. UV protection by nano pigments

5. Color development of organic lakes

6. Conclusions

1. Introduction

Color General Formula Shape Size (m)

Red Fe2O3 Spheroid 0. 2 ~ 0.5

Yellow Fe2O3. H2O Acicular 0.1 ~ 0.25 x 0.6 ~ 0.8

Black FeO . Fe2O3 Spheroid 0. 2 ~ 0.5

Tan ZnO . Fe2O3; MgO . Fe2O3 Acicular 0.2 ~ 0.3 x 1 ~ 1.5

Brown Blend of R,Y and B Mixed 0.2 – 0.5

Common Iron oxides

1. Introduction

Color General Formula Shape Size (m)

Red Fe2O3 Spheroid 0. 2 ~ 0.5

Yellow Fe2O3. H2O Acicular 0.1 ~ 0.25 x 0.6 ~ 0.8

Black FeO . Fe2O3 Spheroid 0. 2 ~ 0.5

Tan ZnO . Fe2O3; MgO . Fe2O3 Acicular 0.2 ~ 0.3 x 1 ~ 1.5

Brown Blend of R,Y and B Mixed 0.2 – 0.5

Common Iron oxides

Pigmentary Titanium Dioxide

Structure: Rutile or AnataseFormula: TiO2

Size: 0.15 - 0.25 m

Higher opacity

Scattering

White light White light

1. TiO2

Generation of color

Refractive Index:

2.76 (R), 2.52 (A)

• White color (or opacity) is generated by scattering light.

• Maximum scattering occurs when the particle size is around 0.2 m.

When size gets smaller, it will loose opacity and get transparent

RedRedWhite light

Color Stronger & Deeper

ScatteringAbsorption

White light

2. Iron Oxides

• Color is generated by both Scattering and Absorption

• Absorption will increases as the size decreases

• Maximum scattering occurs when size is around 0.2 m

R.I.: 2.90 (R), 2.26 (Y), 2.42 (B)

Generation of color

Drawbacks of pigmentary grades

1. High refractive index leads to strong scattering and high opacitywhich results in a dull appearance

2. Large particle size often generates unpleasant skin feel

3. Size reduction can improve skin feel and absorption, but increasethe opacity in most cases.

4. Primary particle size now comes into play

Transparent pigments

Transparent pigments

1. Transparent oxides

Particle size: 100 nm in length, 10 - 20 nm in widthApplication: automotive paints

wood finishesartist coloursindustrial coatingssome plastic applicationscosmetics

Transparent pigments

1. Transparent oxides

Particle size: 100 nm in length, 10 - 20 nm in widthApplication: automotive paints

wood finishesartist coloursindustrial coatingssome plastic applicationscosmetics

2. Transparent TiO2

Particle size: 10 - 60 nm, larger size for some gradesApplication: mainly for use as sunscreens

Common nano iron oxides

Primary Particle Aggregate Agglomerate

Product SupplierPrimary particle

size (m)Mean Particle

Size (m)Trans-oxide Red Cookson Matthey 0.02 x 0.1 54.9Tarox TRR -100 Sakai 0.02 x 0.1 72.5Ferroxide Red Rockwood 0.08 – 0.1 ---

Trans-oxide Yellow Cookson Matthey 0.02 x 0.1 56.9Tarox TRY-100 Sakai 0.02 x 0.1 72.7

Trans-oxide Black Cookson Matthey ~ 0.01 ---Black NF Kobo 0.2 2.1

Ferroxide Orange Rockwood 0.07 ----

New Grade of nano iron oxide

FRO-3-LPConventional

Transparent OxidePigmentary Oxide

Particle shape Spherical Acicular Irregular

Particle size (nm) 30 20 x 100 700Oil Absorption(cc/100g)

14 48 12

Specific SurfaceArea (m2/g)

37 120 3

Less aggregation and easy to disperse

SEM Pictures of Iron Oxides (from Titan Kogyo)

Nano TiO2 for color cosmetics

100nm- High UV-A protection- Low oxidation/photocatalytic activity

- Moderate opacity (to be discussed)

Crystal form Rutile

TiO2 (%) 95-99

Surface Treatment Al(OH)3

Specific Surface Area(m2/g)

23-27

Particle size (nm) 60

KQ-1 from ISK

Nano TiO2 for color cosmetics

Crystal form Rutile

TiO2 (%) 94

Surface Treatment Al(OH)3

Specific Surface Area(m2/g)

130

Particle size (nm) 150

ST-490 from Titan Kogyo

- UV-A protection- Fan shape- Easy to disperse

2. Comparison of color strength

Color Analysis (CIE Lab) of Tint Strength(std: C33-128 Cosmetic Russet; C33-8073 Cosmetic Yellow)

2. Comparison of color strength

Color Analysis (CIE Lab) of Tint Strength(std: C33-128 Cosmetic Russet; C33-8073 Cosmetic Yellow)

-15

-10

-5

0

5

10

15

Δ L Δ a Δ b Δ C Δ H Δ E

Red

Yellow

Color Strength vs. StdTrans Red 49.0%

Trans Yellow 83.5%

2. Comparison of color strength

Color Analysis (CIE Lab) of Tint Strength(std: C33-128 Cosmetic Russet; C33-8073 Cosmetic Yellow)

-15

-10

-5

0

5

10

15

Δ L Δ a Δ b Δ C Δ H Δ E

Red

Yellow

Color Strength vs. StdTrans Red 49.0%

Trans Yellow 83.5%

-10

-5

0

5

10

15

Δ L Δ a Δ b Δ C Δ H Δ E

Red

Yellow

Color Strength vs. StdTRR-100 56.9%TRY-100 84.6%

0

5

10

15

20

25

30

35

L a b

Premix 1 2 3

No effect of additional grindingcan be observedPremix 1st 2nd 3rd

19 0.54 0.53 0.51 m

1. 75% ITT treated red iron oxide in cyclomethicone2. Dispersant : KP-575

Iron oxide dispersion (CMKP75R) -effect of size

Color Analysis (CIE Lab) of Masstone

More grinding makes color

• Darker

• Bluer

Dried Drawdown

0

10

20

30

40

L a b

Premix 1 2 3

Premix 1st 2nd 3rd19 0.54 0.53 0.51 m

CMKP75R Dispersion : Masstone

0

20

40

60

L a b

Premix 1st 2nd

• Similar to dried masstone

• More grinding results inhigher color strength

Iron oxide : TiO2 = 15 :85

Premix 1st 2nd 3rd

CMKP75R : Tint strength comparison

Color Analysis of Tint Strength

95

96

97

98

99

Premix 1st 2nd

0

0.2

0.4

0.6

0.8

Siz

e( m

m)

L Size

• More grinding results inslightly lower brightness

• Crowding effect

Dispersant: Abil EM 97Solids: 70%

Premix 1st 2nd

Silane treated TiO2 dispersion : Effect of Size

Color and Size Analysis

L

45

47

49

51

53

Premix 1st 2nd

-10

-8

-6

-4

-2

0

a b

Premix 1st 2nd

More grinding Higher opacity(Opposite to masstone)Bluer Color

TiO2 : Black iron oxide = 85 :15

Premix 1st 2nd

Tint strength comparison : silane treated TiO2

• General mechanism :

› Shear force

› Impact action

• Formulation Considerations :

› Primary particle size

› Surface treatment

› Carrier

› Dispersant

3. Dispersion of the pigment and color development

Chunky paste

Chunky paste

Viscous slurry

Fluid

w/o

dis

per

san

tw

/d

isp

ers a

nt

A B

C D

15nm TiO2 : 45% *

Treatment : Methicone (B & D)

Vehicle : Cyclopentasiloxane

Dispersant : 10 % KF-6017 (C & D)

* note : in mix A, only 33% TiO2was used (maximum amountpossible)

Untreated Treated

Surface Treatment -- Pre-Wetting of the Pigment

Easy handlingBetter dispersion

Common surface treatments

ChemicalSurface

property

Compatible

vehicle

Metal Soap (AHSA)

Isopropyl Titanium

Triisostearate

LipophilicEster

Oil

Organic

coating

Methicone

Dimethicone

Triethoxy Caprylylsilane

HydrophobicSilicones

Ester

C9-15 Fluoroalcohol phosphateLipophobic and

HydrophobicSilicones

Simethicone Amphoteric

Water

Oil

Silicones

Triethanolamine

PolyolHydrophilic Water

Inorganic

coating

Silica

Alumina

Zirconium oxide

Sodium hexametaphosphate

Hydrophilic Water

Effect of size on surface treatment and dispersibility

Nano pigment:• Small primary particle size, large surface area• High surface energy for more severe aggregation and reactivity

Surface treatment: Needs more coatingDispersion: Low pigment load and hard to grind

Pigment Surface Area% of

CoatingSolids% inDC 5225C

C33-218 Cosmetic Russet < 10 m2/g 1 –2 70

Trans-oxide Red ~ 80 m2/g 10 30

Nano iron oxide in C12-15 alkyl benzoate

Iron Red Iron YellowTN45TOR T N70R TN45TOY TN55Y

Raw Pigment Transoxide Pigmentary Transoxide PigmentarySurface treatment TCS ITT TCS ITTSolids,% 45 70 45 70Viscosity, cPs 178,400 247,000 210,000 85,000Dispersion size (nm) 112 290 102 350

TCS: triethoxy carprylylsilane; ITT: isopropyl titanium dioxide

TN45TOR TN70R TN45TOY TN55Y

-10

-5

0

5

10

15

20

Δ L Δ a Δ b Δ C Δ H Δ E

TN45TOR

TN45TOY

Nano iron oxides in ester ---tint strength

TN45TOY TN55Y

TN45TOR TN70R

TN45TOY TN55Y

Color Analysis (CIE Lab) of Tint Strength

Color Strength vs. StdTrans Red 69.3%

Trans Yellow 120.2%

Dispersion of 100 nm TiO2

DispersionPPS(nm)

Surfacetreatment

PS(nm)

%

INH65K9 100 ITT/w s 190 65

IN80C 170 ITT 263 80

Dispersion inIsononyl Isononanoate

INH65K9 IN80C-6

-4

-2

0

2

4

6

Δ L Δ a Δ b Δ C Δ H Δ E

Color Analysis of Tint Strength

TiO2 : Iron black = 85 : 15

Result: Less opaque, bluer

Dispersion inCyclomethicone

CM3K50KQM CM3FA70STC

DispersionPPS(nm)

Surfacetreatment

PS(nm)

%

CM3K50KQM 60 MS 185 50

CM3FA70STC 170 MS 280 70

Dispersion of 60 nm TiO2

-8

-6

-4

-2

0

2

4

6

8

Δ L Δ a Δ b Δ C Δ H Δ E

Color Analysis of Tint Strength

TiO2 : Iron black = 85 : 15

Result: much less opaque and more bluer

4. UV Protection from nano pigments

0

20

40

60

80

100

280 320 360 400 440 480 520 560 600 640 680

Wavelength (nm)

T%

0.001%

UV Visible

Nano Yellow

Nano red

Pig. yellow

Pig. red

UV/Vis transmittance curves of nano iron oxides

UV/Vis transmittance curves - TiO2 Dispersions

0

20

40

60

80

100

280 320 360 400 440 480 520 560 600 640 680

Wavelength (nm)

T%

UV Visible

PPS:

60 nm

100 nm

180 nm

Premix Milled

5. Color development of organic lakes

Raw Pigment Red 6 Ba Lake

Surface treatment ITT

Solids,% 30

Dispersion size (nm) 386

Red 6 lake in synthetic wax(SW30R6B) Formula

* Size of powder: 3 - 6 microns.

Gloss and feel are much improved as particle size getsmilled down.

-2

0

2

4

6

8

DL* Da* Db* DC DH DE

Masstone

-4

-2

0

2

4

6

8

DL* Da* Db* DC DH DE

Tint Strength

Color development of lakes - Dispersion vs. Powder

Color property --Red 6 Ba lake dispersion vs. powder

Color strength is greatly increased when the particle sizeis reduced to submicron

Conclusions:

Conclusions:

1. Nano pigments have their unique properties and requiremore considerations in:

• Surface treatment• Color development

Conclusions:

1. Nano pigments have their unique properties and requiremore considerations in:

• Surface treatment• Color development

2. Nano pigments can provide more UVA protection and helpboost SPF.

Conclusions:

1. Nano pigments have their unique properties and requiremore considerations in:

• Surface treatment• Color development

2. Nano pigments can provide more UVA protection and helpboost SPF.

3. Milling organic lakes is important for their color development.

Conclusions:

1. Nano pigments have their unique properties and requiremore considerations in:

• Surface treatment• Color development

2. Nano pigments can provide more UVA protection and helpboost SPF.

3. Milling organic lakes is important for their color development.

4. Although nano pigments have been available on marketplacefor many years, use in cosmetics still needs to be explored.