Colorant Basics for Cosme0cs

Transcription

1 Society of Cosme-c Chemists Intermountain West Chapter Colorant Basics for Cosme0cs September 9, 2015

2 AGENDA ITEMS Toners, True Pigments, Dyes and Lakes Inorganic Colorants Color Structure Differences CFR 21 Parts 73 & 74 Regula0ons Color Nomenclature Pigment Processing Milling Methods Par0cle Electrosta0c Charge / Zeta Poten0al Solvents Under- milling / Over- milling Color Stability Links to FDA Color Informa0on

3 Color Additives Ingredients designed to impart color Are regulated globally Different markets have different regula0ons Dyes and Pigments Can be synthe0c or natural

4 Dyes versus Pigments» A dye is a material that imparts a color and is soluble in the vehicle or substrate in which it is dispersed.» A pigment is a material that is insoluble in the vehicle or substrate in which it is dispersed. In the U.S. synthetic colors are called FD&C, D&C or External D&C Colors: Food, Drug & Cosmetic or Drug & Cosmetic Colors.

5 Synthetic Organic Colorants All synthe-c organic colorants are subject to lot to lot Cer-fica-on by the U. S. Food and Drug Administra-on» Toners» True Pigments» Dyes» Lakes

6 Toners Toners are pigments that are produced by precipitating a water soluble dye as a metal salt. Typical metals used for this precipitation are sodium, calcium, barium and strontium. Toners are capable of complete insolubility without the aid of a substrate. The practice in the cosmetic industry is to dilute the toners in an inert substance, or base, to reduce their intensity, improve their dispersaibility and grinding properties or change their opacity. Materials commonly used for this purpose are barium sulfate, alumina hydrate, talc or rosin to produce colorants with a varied range of hues and dye strengths. Examples of toners are D&C Red No. 6 Barium Lake, D&C Red No. 7 Calcium Lake and D&C Red No. 34 Calcium Lake.

7 Toners Differences between D&C Red Nos. 6 & 7 Acceptability in Japan Technically they are all considered Pigment Red 57 / CI D&C Red No. 6 Sodium Salt (Permitted in Japan - Red 201) - This is the starting point for both colorants. D&C Red No. 6 Barium Salt (Prohibited in Japan) Base is Barium Sulfate; Barium salt not allowed. D&C Red No. 7 Calcium Salt (Red 202 in Japan) Base can be Alumina or Rosin. Note: None of these can be called Lakes in Japan In terms of color, D&C Red No. 6 is to the yellow/orange side while D&C Red No. 7 is to the blue/red side. D&C Red No. 6 Sodium Salt D&C Red No. 6 Barium Lake D&C Red No. 7 Calcium Lake

8 True Pigments True pigments are those colorants that are completely insoluble based on their chemical structure and constituent groups. True pigments typically do not contain the normal substitution groups that promote water solubility, such as sulfonates (-SO3), carboxylic acid (-COOH) or hydroxyl groups (-OH). Hence, there is no bleeding in hydrous systems. It has good overall stability in emulsions. There are only two examples of true pigments used in cosmetics: These are D&C Red No. 30 and D&C Red No. 36. True pigments are normally used full strength (as is) without any diluents, but can be blended with talc or alumina hydrate to aid in grinding and reduce color strength.

9 Examples of Dyes Water Soluble Dyes FD&C Red Nos. 4 & 40 FD&C Yellow Nos. 5 & 6 FD&C Blue No. 1, 2 FD&C Green No. 3 D&C Red Nos. 21, 22, 27, 28, 31, 33 D&C Orange No. 4 D&C Yellow Nos. 7, 10 D&C Green Nos. 5, 8 Ext. D&C Violet No. 2 Oil Soluble Dyes D&C Red No. 17 D&C Violet No. 2 D&C Green No. 6 D&C Yellow No. 11

10 LAKE = water soluble dye + insoluble substrate = INSOLUBLE PIGMENT This is not a chemical bond as with mica- based pigments but an adsorp-on onto an insoluble material. Absorp-on versus Adsorp-on

11 Lakes 10 FDA Approved Substrates Permitted to Produce Lakes Talc Aluminum Hydrate * Aluminum Benzoate Barium Sulfate Titanium Dioxide Gloss White Calcium Carbonate Zinc Oxide Clay Rosin * Aluminum Hydroxide (Alumina) is the only substrate permitted for the production of FD&C Lakes. These substrates have global acceptability and can also be used as regular fillers in a cosmetic formulation.

12 Colorants Exempt from FDA Certification Titanium Dioxide Iron Oxides Chrome Oxides & Hydroxides Zinc Oxide Ultramarines Manganese Violet Ferric Ferrocyanide Carmine* All inorganic colorants are insoluble pigments. Inorganic colorants used today are mainly synthetic because they are cheaper to manufacture, have better stability, more consistent color control and it is easier to meet FDA guidelines for safety, purity and heavy metal content.

13 Similarities in Organic Colorants Xanthene Dyes (Fluorescein Dyes with Halogen Substitutions) x4 x4 x4 FD&C Red No. 3 Tetraiododfluorescein (or Erythrosine) D&C Red No. 21 & 22 Tetrabromofluorescein D&C Red No. 27 & 28 Tetrabromotetrachlorofluorescein The difference between D&C Orange No. 5 and D&C Red No. 22 is two less Bromine atoms; Therefore D&C Orange No. 5 is called Dibromofluorescein

14 Similarities in Organic Colorants Monoazo Dyes x2 NO2 NO2 D&C Orange No. 4 FD&C Yellow No. 6 Monoazo Dyes D&C Orange No. 17 (delisted) FD&C Yellow No. 6 (Same structure as above but from a different view) FD&C Red No. 40

15 Similarities in Organic Colorants Anthraquinones D&C Violet No. 2 (Oil Soluble) Ext. D&C Violet No. 2 (Water Soluble)

16 Front Page

17 Color Nomenclature Regulations Colorant nomenclature in the US: Uncertified Chemical Name Vat Red 1 Certified Name D&C Red No. 30 from CTFA Cosmetic Ingredient Dictionary Colorant nomenclature is different in other markets: D&C Red No. 30 CI Red 226 U.S. Name EU Name (CI Number) Japan Name Cannot use in area of the eye Eye area use o.k. from CTFA International Color Handbook Mixtures of D&C Red No. 30 and Talc or Alumina Hydrate cannot be called Lakes in Japan. But they can be called Blends as Lakes of D&C Red No. 30 do not exist. Some suppliers were calling these mixtures D&C Red No. 30 Aluminum Lake or Talc Lake which is incorrect.

18 Pigment Processing As supplied, pigments are highly agglomerated and sometimes aggregated Particle size can be as high as 100 microns or more Primary Particle Aggregate - Tightly Bound Agglomerate - Loosely Associated

19 Pigment Processing To obtain op0mum color strength and performance a par0cle size of 3 to 5 microns must be achieved. There are various methods that can be u0lized for the proper grinding of pigments: Ball Mills, Media Mills, 3- Roll Mills First one must understand pigments and how they interact with their surroundings.

20 Zeta Potential and Particle Interaction Zeta potential is the difference in electrical potential between the dispersed medium and the stationary layer of fluid attached to a dispersed pigment particle. Many particles have an electrostatic charge. Zeta potential which is measured in millivolts (mv) is the charge that develops at the interface between a solid s surface and the liquid medium it is dispersed in. A zeta potential of ~25 mv is said to be the borderline value to determine if an emulsion will remain stable. The significance of zeta potential is that its value can be related to the stability of colloidal dispersions, especially makeup emulsions. The zeta potential indicates the degree of attraction or repulsion between adjacent, similarly charged particles, such as pigments and dry powder fillers, in dispersions and similar colloidal systems.

21 Zeta Potential When the potential is low, particle attraction exceeds repulsion and the dispersion will break, flocculate and separate (see chart below). Dispersions with high zeta potential (negative or positive) are electrically stabilized while colloids with low zeta potentials tend to separate. Increasing the zeta potential improves an emulsion s stability. Zeta potential can be regulated or altered using salts which at high levels will reduce the electrical potential, or by coating the particles with polymers or surface treatments thereby causing steric repulsion where van der Waals forces are too weak to cause the particles to adhere to one another. Particles will separate if they are more dense than the medium, or creaming will occur if they are less dense. Zeta Potential (mv) Stability Behavior of the Colloid from 0 to ±5 Rapid coagulation or flocculation from ±10 to ±30 Some instability from ±30 to ±40 Moderate stability from ±40 to ±60 Good stability more than ±61 Excellent stability

22 3-Roll Mill for Wet Grinding In order to get down to the primary particle size, this is one of the grinding methods that must be utilized. Operation of a large 3-Roll Mill at a manufacturing facility in China

23 Laboratory / Benchtop Roller Mills EXAKT 50 Benchtop Mill Total Mill Width: 12 inches Standard Benchtop Mill Notice knobs at each roller adjustment point. The EXAKT 3-roll mill settings are easier to adjust as they are parallel (one roller closes in on the next = 2 settings) whereas other 3-roll mills (Ross or Keith Machinery) must be adjusted at each roller end (4 adjustments to close settings).

24 3-Roll Mill Operation Used for grinding insoluble pigments in a suitable liquid or other solvents. The grinding process produces its best results when the dispersions are high viscosity pastes. This process generates some heat. The rollers can be cooled or heated with recirculating water. The normal milling process usually requires a minimum of two passes. Sometimes three passes may be needed for some harder pigments. Discharge Feed Apron / Knife Roller Mechanism NOTE: Roller Mill Safety procedures must be followed at all times.

25 Hoover Muller The Hoover Muller provides a quick and easy method for preparing a very small sample (1 to 2 grams) of a pigment-solvent dispersion. The top plate remains stationery while the bottom plate rotates. The pigments are ground between the two glass plates as it rotates. The glass plates that shear and grind the pigments into the solvent are easily cleaned by a wetting agent or other suitable solvent. This equipment is ideal for Lab or QC use to evaluate incoming pigment lots.

26 Hegman Gauge Left Well Scale: Reading 6-8 Right Well Scale: 0-25 Microns

27 Hegman Gauge Ø Used in many different industries to determine the acceptability and fineness of grind after wet milling. Ø Ideal for use with higher viscosity wet / paste dispersions. Ø Depending on the gauge, the best reading should be: 7 to 8 on the NS or H Scale (left well) < 10 microns particle size (right well) Ø Acceptability is evident with the lack of streaking above 7 on the drawdown NS or H Scale. Ø Avoid dust particles in the sample when reading gauge.

28 Colloid Mill Used for wet grinding systems which are Fluid and have a much lower viscosity than with 3-roll or ball mills. Can be hopper-type (shown below) or in-line type. This mill works on a Rotor-Stator principle. The rotor has very sharp teeth and spins at very high rpm s and moves to close the gap while the stator stays in place to accept the gap reduction from the rotor. The smaller the gap the more heat that is produced. This gap can close to within thousandths of an inch to grind pigments down to their primary particle size. Grind is checked using a drawdown method or between 2 glass microscope slides to check for unground pigment specks. Ideal for foundations, liquid makeup, eye products or any other fluid systems. Gifford-Wood Hopper-Type Colloid Mill Rotor Rotor-Stator Assembly Stator

29 Automatic Drawdown Apparatus Usually supplied with rods that are coiled with different thickness of wire that determines film thickness. Thicker wire creates a thicker film (more flow between wires). Apparatus can apply heat to the film and have variable speeds. Ideal for lower viscosity materials and fluids.

30 Drawdown Methods Fixed Thickness Applicators Adjustable Thickness Rods Adjustable Thickness Applicators Drawdowns must create repeatable and reproducible films. Films can be created using manual or automatic methods. After a drawdown film has been deemed acceptable, it can be used for visual color comparison or computer measurement.

31 Problems Caused by Poor Grinding Difficult to Duplicate Shades Shades will not match the color reference standard if the optimum particle size has not been achieved. Constant mixing or over-mixing with excess heat can continue to develop color but it will never match standard. Mass / Skintone Differences (Color Reversals) If optimum particle size has not been achieved masstone and skintone will not match. The color will continue to develop and intensify on skin during application and will not match bulk tone. This is what we call chasing a moving target as the color on skin will always look different than the bulk or mass tone. Ways to Prevent Color Issues Always check finess of grind with the proper equipment, on the skin, or by performing a drawdown. There should never be color specks or streaks in the color grind, otherwise it will require further processing and grinding. Product Instability Larger particles may agglomerate and cause phase separation.

32 Jet Mills for Dry Grinding The main advantage of using a Jet Mill for pressed powders is that you cannot get as small a particle size with any other type of processing equipment or grinding apparatus. This process requires only 1 pass and can consistently produce particles between 0.5 and 1 micron in size. Jet milling is not an actual grinding process such as with hammer mills. It is a bombardment of particles against one another and against a metal plate reducing their particle size and shape significantly. Jet Milling produces a pressed powder with very elegant feel properties due to the powder particles spherical shape. Usually utilized exclusively for pressed powder foundations. You cannot get a better feel out of a product using any other process.

33 Solvents Ideal solvents provide the best results when we4ng and grinding pigments Castor Oil Polar Solvents / Esters Lanolin Oil Glycols Glycerin Surface Treatments We[ng Agents

34 Over-Milling Pigment Grinding When using the proper equipment and techniques, over- milling is virtually impossible. Today s grinding equipment is very efficient. Op0mum par0cle size yields maximum color development. Under- milling will create par0cles too large and creates issues such as we just explained. However, as par0cles become smaller they lose color value and become more transparent such as with micronized zinc oxide, 0tanium dioxide and iron oxides. This requires special equipment.

35 Color Stability Light, Heat and Chemical Stability Most organic and Inorganic colorants are heat stable Can be used in emulsions and hot pour products with extended high temperatures Some organic colorants have poor light stability D&C Red 21, 22, 27, 28, FD&C Blue 1 Most organic colorants are acid stable Hence the term Acid Dyes Some colorants are unstable in Alkaline ph Ultramarines, Ferric Ferrocyanide Colorants should always go in the external phase of an emulsion In the internal phase they will fade and disappear Some colorants are stable under many condi0ons Titanium Dioxide, Iron Oxides, D&C Red 30

36 Links to Important Color Informa-on v Link to FDA Color Addi-ves Sec-on: v Link to CFR 21 Front Page: v Link to FDA Color Cer-fica-on Records: ColorCer-fica-onReports/default.htm